Initial Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

LLM Generation

Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

Output

Here's a C implementation of the RREF (Reduced Row Echelon Form) function: 

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#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int* pivots = malloc(rows * sizeof(int));
    int pivots_count = 0;

    // Create used_for_row sets
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        memset(used_for_row[i], 0, rows * sizeof(int));
        used_for_row[i][i] = 1;
    }

    // Reduce matrix modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Handle zero columns
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            int all_zero = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = 0;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find non-zero row to swap
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
        }

        pivots[pivots_count++] = col + extra;

        // Handle pivot
        int pivot = matrix[col][col + extra];
        if (col + extra < graphlen) {
            assert(abs(pivot) == 1 || abs(pivot) == PH - 1);
        } else {
            assert(abs(pivot) == 2 || abs(pivot) == PH - 2);
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            // Merge used_for_row sets
            for (int j = 0; j < rows; j++) {
                if (used_for_row[col][j]) {
                    used_for_row[i][j] = 1;
                }
            }

            // Reduce row
            if (matrix[i][col + extra] != 0) {
                if (col < graphlen) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                        matrix[i][j] %= PH;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        }
                    }
                }
            }
        }

        col++;
    }

    // Reduce matrix modulo PH again
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    // Convert used_for_row to sorted lists
    int** sorted_used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        sorted_used_for_row[i] = malloc(rows * sizeof(int));
        int count = 0;
        for (int j = 0; j < rows; j++) {
            if (used_for_row[i][j]) {
                sorted_used_for_row[i][count++] = j;
            }
        }
        sorted_used_for_row[i][count] = -1;  // Mark end of list
    }

    // Free intermediate memory
    for (int i = 0; i < rows; i++) {
        free(used_for_row[i]);
    }
    free(used_for_row);
    free(pivots);

    return sorted_used_for_row;
}
This implementation follows the same logic as the Python version with a few key differences: 1. Sets are replaced with integer arrays where 1 indicates membership and 0 indicates non-membership. 2. The function returns a 2D array where each row is a sorted list of indices, terminated by -1. 3. Memory management is more explicit in C. Note: This implementation assumes the caller will: - Provide a valid matrix - Free the returned memory after use - Handle any potential memory allocation failures Example usage: 
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int rows = 3, cols = 4, graphlen = 2;
int** matrix = malloc(rows * sizeof(int*));
for (int i = 0; i < rows; i++) {
    matrix[i] = malloc(cols * sizeof(int));
    // Initialize matrix...
}

int** result = rref(matrix, rows, cols, graphlen);

// Use result...

// Free memory
for (int i = 0; i < rows; i++) {
    free(result[i]);
    free(matrix[i]);
}
free(result);
free(matrix);

Extract Code

I extracted the following code from that output: 

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#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int* pivots = malloc(rows * sizeof(int));
    int pivots_count = 0;

    // Create used_for_row sets
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        memset(used_for_row[i], 0, rows * sizeof(int));
        used_for_row[i][i] = 1;
    }

    // Reduce matrix modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Handle zero columns
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            int all_zero = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = 0;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find non-zero row to swap
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
        }

        pivots[pivots_count++] = col + extra;

        // Handle pivot
        int pivot = matrix[col][col + extra];
        if (col + extra < graphlen) {
            assert(abs(pivot) == 1 || abs(pivot) == PH - 1);
        } else {
            assert(abs(pivot) == 2 || abs(pivot) == PH - 2);
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            // Merge used_for_row sets
            for (int j = 0; j < rows; j++) {
                if (used_for_row[col][j]) {
                    used_for_row[i][j] = 1;
                }
            }

            // Reduce row
            if (matrix[i][col + extra] != 0) {
                if (col < graphlen) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                        matrix[i][j] %= PH;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        }
                    }
                }
            }
        }

        col++;
    }

    // Reduce matrix modulo PH again
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    // Convert used_for_row to sorted lists
    int** sorted_used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        sorted_used_for_row[i] = malloc(rows * sizeof(int));
        int count = 0;
        for (int j = 0; j < rows; j++) {
            if (used_for_row[i][j]) {
                sorted_used_for_row[i][count++] = j;
            }
        }
        sorted_used_for_row[i][count] = -1;  // Mark end of list
    }

    // Free intermediate memory
    for (int i = 0; i < rows; i++) {
        free(used_for_row[i]);
    }
    free(used_for_row);
    free(pivots);

    return sorted_used_for_row;
}

Run Code Interpreter

Running the following program: 

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#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int* pivots = malloc(rows * sizeof(int));
    int pivots_count = 0;

    // Create used_for_row sets
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        memset(used_for_row[i], 0, rows * sizeof(int));
        used_for_row[i][i] = 1;
    }

    // Reduce matrix modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Handle zero columns
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            int all_zero = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = 0;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find non-zero row to swap
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
        }

        pivots[pivots_count++] = col + extra;

        // Handle pivot
        int pivot = matrix[col][col + extra];
        if (col + extra < graphlen) {
            assert(abs(pivot) == 1 || abs(pivot) == PH - 1);
        } else {
            assert(abs(pivot) == 2 || abs(pivot) == PH - 2);
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            // Merge used_for_row sets
            for (int j = 0; j < rows; j++) {
                if (used_for_row[col][j]) {
                    used_for_row[i][j] = 1;
                }
            }

            // Reduce row
            if (matrix[i][col + extra] != 0) {
                if (col < graphlen) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                        matrix[i][j] %= PH;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        }
                    }
                }
            }
        }

        col++;
    }

    // Reduce matrix modulo PH again
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    // Convert used_for_row to sorted lists
    int** sorted_used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        sorted_used_for_row[i] = malloc(rows * sizeof(int));
        int count = 0;
        for (int j = 0; j < rows; j++) {
            if (used_for_row[i][j]) {
                sorted_used_for_row[i][count++] = j;
            }
        }
        sorted_used_for_row[i][count] = -1;  // Mark end of list
    }

    // Free intermediate memory
    for (int i = 0; i < rows; i++) {
        free(used_for_row[i]);
    }
    free(used_for_row);
    free(pivots);

    return sorted_used_for_row;
}



#include<stdio.h>
#include<stdlib.h>

int main() {

int arr0[] = {1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr1[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr2[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr3[] = {0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr4[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr5[] = {0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr6[] = {0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0};
int arr7[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, -30};
int arr8[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr9[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, -20};
int arr10[] = {1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr11[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr12[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr13[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -14};
int arr14[] = {0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr15[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, -30};
int arr16[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr17[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr18[] = {0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr19[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr20[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr21[] = {0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr22[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, -20};
int arr23[] = {0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr24[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr25[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr26[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr27[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr28[] = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr29[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr30[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr31[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr32[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, -10};
int arr33[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr34[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr35[] = {0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -9};
int arr36[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, -20};
int arr37[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, -40};
int arr38[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int* arr[] = {arr0, arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10, arr11, arr12, arr13, arr14, arr15, arr16, arr17, arr18, arr19, arr20, arr21, arr22, arr23, arr24, arr25, arr26, arr27, arr28, arr29, arr30, arr31, arr32, arr33, arr34, arr35, arr36, arr37, arr38};
int** got = rref(arr, 39, 49, 37);


int answer = got[3][0]+got[3][1]+got[3][2]+got[3][3]+got[3][4]+got[3][5]+got[3][6];
int expected = 146;
if (answer != expected) {
    printf("Wrong answer; got %d instead of %d.\n", answer, expected);
    exit(1);
}
printf("All tests passed\n");
}
And got the output: Wrong answer; got 21 instead of 146.

Substring Evaluation

Testing if the previous output contains the string All tests passed: False

Initial Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

LLM Generation

Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

Output

Here's a C implementation of the RREF (Reduced Row Echelon Form) function: 

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#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int** used_for_row = malloc(rows * sizeof(int*));
    int* used_for_row_sizes = malloc(rows * sizeof(int));

    // Initialize used_for_row
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row_sizes[i] = 1;
    }

    // Apply modulo PH to matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Check if current pivot is zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find a non-zero row to swap
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row entries
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
            
            int temp_size = used_for_row_sizes[col];
            used_for_row_sizes[col] = used_for_row_sizes[other];
            used_for_row_sizes[other] = temp_size;
        }

        int pivot = matrix[col][col + extra];
        
        // Validate pivot based on graphlen
        if (col + extra < graphlen) {
            if (abs(pivot) != 1 && abs(pivot) != PH - 1) {
                // Handle error or assert
                exit(1);
            }
        } else {
            if (abs(pivot) != 2 && abs(pivot) != PH - 2) {
                // Handle error or assert
                exit(1);
            }
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            if (matrix[i][col + extra] != 0) {
                // Merge used_for_row sets
                for (int j = 0; j < used_for_row_sizes[col]; j++) {
                    bool found = false;
                    for (int k = 0; k < used_for_row_sizes[i]; k++) {
                        if (used_for_row[i][k] == used_for_row[col][j]) {
                            found = true;
                            break;
                        }
                    }
                    if (!found) {
                        used_for_row[i][used_for_row_sizes[i]++] = used_for_row[col][j];
                    }
                }

                // Eliminate row
                if (col + extra < graphlen) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                        matrix[i][j] %= PH;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        }
                    }
                }
            }
        }

        col++;
    }

    // Apply final modulo
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    // Sort used_for_row entries
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < used_for_row_sizes[i] - 1; j++) {
            for (int k = 0; k < used_for_row_sizes[i] - j - 1; k++) {
                if (used_for_row[i][k] > used_for_row[i][k + 1]) {
                    int temp = used_for_row[i][k];
                    used_for_row[i][k] = used_for_row[i][k + 1];
                    used_for_row[i][k + 1] = temp;
                }
            }
        }
    }

    // Free temporary size array
    free(used_for_row_sizes);

    return used_for_row;
}
Key differences from the Python implementation: 1. Manual memory management with `malloc()` and `free()` 2. Explicit iteration instead of NumPy functions 3. Separate tracking of used_for_row sizes 4. Manual sorting of used_for_row entries 5. Modulo and scaling operations manually implemented Note that this implementation assumes: - Input matrix is pre-allocated - Caller is responsible for freeing the returned `used_for_row` memory - Basic error handling (exiting on invalid pivot) You would call this function like: 
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int rows = ..., cols = ...;
int** matrix = malloc(rows * sizeof(int*));
for (int i = 0; i < rows; i++) {
    matrix[i] = malloc(cols * sizeof(int));
    // Initialize matrix
}

int graphlen = ...;
int** used_for_row = rref(matrix, rows, cols, graphlen);

// Use used_for_row

// Free memory
for (int i = 0; i < rows; i++) {
    free(matrix[i]);
    free(used_for_row[i]);
}
free(matrix);
free(used_for_row);

Extract Code

I extracted the following code from that output: 

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#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int** used_for_row = malloc(rows * sizeof(int*));
    int* used_for_row_sizes = malloc(rows * sizeof(int));

    // Initialize used_for_row
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row_sizes[i] = 1;
    }

    // Apply modulo PH to matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Check if current pivot is zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find a non-zero row to swap
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row entries
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
            
            int temp_size = used_for_row_sizes[col];
            used_for_row_sizes[col] = used_for_row_sizes[other];
            used_for_row_sizes[other] = temp_size;
        }

        int pivot = matrix[col][col + extra];
        
        // Validate pivot based on graphlen
        if (col + extra < graphlen) {
            if (abs(pivot) != 1 && abs(pivot) != PH - 1) {
                // Handle error or assert
                exit(1);
            }
        } else {
            if (abs(pivot) != 2 && abs(pivot) != PH - 2) {
                // Handle error or assert
                exit(1);
            }
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            if (matrix[i][col + extra] != 0) {
                // Merge used_for_row sets
                for (int j = 0; j < used_for_row_sizes[col]; j++) {
                    bool found = false;
                    for (int k = 0; k < used_for_row_sizes[i]; k++) {
                        if (used_for_row[i][k] == used_for_row[col][j]) {
                            found = true;
                            break;
                        }
                    }
                    if (!found) {
                        used_for_row[i][used_for_row_sizes[i]++] = used_for_row[col][j];
                    }
                }

                // Eliminate row
                if (col + extra < graphlen) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                        matrix[i][j] %= PH;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        }
                    }
                }
            }
        }

        col++;
    }

    // Apply final modulo
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    // Sort used_for_row entries
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < used_for_row_sizes[i] - 1; j++) {
            for (int k = 0; k < used_for_row_sizes[i] - j - 1; k++) {
                if (used_for_row[i][k] > used_for_row[i][k + 1]) {
                    int temp = used_for_row[i][k];
                    used_for_row[i][k] = used_for_row[i][k + 1];
                    used_for_row[i][k + 1] = temp;
                }
            }
        }
    }

    // Free temporary size array
    free(used_for_row_sizes);

    return used_for_row;
}

Run Code Interpreter

Running the following program: 

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#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int** used_for_row = malloc(rows * sizeof(int*));
    int* used_for_row_sizes = malloc(rows * sizeof(int));

    // Initialize used_for_row
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row_sizes[i] = 1;
    }

    // Apply modulo PH to matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Check if current pivot is zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find a non-zero row to swap
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row entries
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
            
            int temp_size = used_for_row_sizes[col];
            used_for_row_sizes[col] = used_for_row_sizes[other];
            used_for_row_sizes[other] = temp_size;
        }

        int pivot = matrix[col][col + extra];
        
        // Validate pivot based on graphlen
        if (col + extra < graphlen) {
            if (abs(pivot) != 1 && abs(pivot) != PH - 1) {
                // Handle error or assert
                exit(1);
            }
        } else {
            if (abs(pivot) != 2 && abs(pivot) != PH - 2) {
                // Handle error or assert
                exit(1);
            }
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            if (matrix[i][col + extra] != 0) {
                // Merge used_for_row sets
                for (int j = 0; j < used_for_row_sizes[col]; j++) {
                    bool found = false;
                    for (int k = 0; k < used_for_row_sizes[i]; k++) {
                        if (used_for_row[i][k] == used_for_row[col][j]) {
                            found = true;
                            break;
                        }
                    }
                    if (!found) {
                        used_for_row[i][used_for_row_sizes[i]++] = used_for_row[col][j];
                    }
                }

                // Eliminate row
                if (col + extra < graphlen) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                        matrix[i][j] %= PH;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        }
                    }
                }
            }
        }

        col++;
    }

    // Apply final modulo
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    // Sort used_for_row entries
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < used_for_row_sizes[i] - 1; j++) {
            for (int k = 0; k < used_for_row_sizes[i] - j - 1; k++) {
                if (used_for_row[i][k] > used_for_row[i][k + 1]) {
                    int temp = used_for_row[i][k];
                    used_for_row[i][k] = used_for_row[i][k + 1];
                    used_for_row[i][k + 1] = temp;
                }
            }
        }
    }

    // Free temporary size array
    free(used_for_row_sizes);

    return used_for_row;
}



#include<stdio.h>
#include<stdlib.h>

int main() {

int arr0[] = {1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr1[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr2[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr3[] = {0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr4[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr5[] = {0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr6[] = {0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0};
int arr7[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, -30};
int arr8[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr9[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, -20};
int arr10[] = {1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr11[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr12[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr13[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -14};
int arr14[] = {0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr15[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, -30};
int arr16[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr17[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr18[] = {0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr19[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr20[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr21[] = {0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr22[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, -20};
int arr23[] = {0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr24[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr25[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr26[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr27[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr28[] = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr29[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr30[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr31[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr32[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, -10};
int arr33[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr34[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr35[] = {0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -9};
int arr36[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, -20};
int arr37[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, -40};
int arr38[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int* arr[] = {arr0, arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10, arr11, arr12, arr13, arr14, arr15, arr16, arr17, arr18, arr19, arr20, arr21, arr22, arr23, arr24, arr25, arr26, arr27, arr28, arr29, arr30, arr31, arr32, arr33, arr34, arr35, arr36, arr37, arr38};
int** got = rref(arr, 39, 49, 37);


int answer = got[3][0]+got[3][1]+got[3][2]+got[3][3]+got[3][4]+got[3][5]+got[3][6];
int expected = 146;
if (answer != expected) {
    printf("Wrong answer; got %d instead of %d.\n", answer, expected);
    exit(1);
}
printf("All tests passed\n");
}
And got the output: Wrong answer; got 67 instead of 146.

Substring Evaluation

Testing if the previous output contains the string All tests passed: False

Initial Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

LLM Generation

Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

Output

Here's a C implementation of the `rref` function based on the Python code you provided: 

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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

#define PH 16

// Helper function to create a set-like structure
typedef struct {
    int* elements;
    int size;
    int capacity;
} Set;

Set* create_set(int initial_capacity) {
    Set* set = malloc(sizeof(Set));
    set->elements = malloc(initial_capacity * sizeof(int));
    set->size = 0;
    set->capacity = initial_capacity;
    return set;
}

void set_add(Set* set, int element) {
    // Check if element already exists
    for (int i = 0; i < set->size; i++) {
        if (set->elements[i] == element) return;
    }

    // Resize if needed
    if (set->size == set->capacity) {
        set->capacity *= 2;
        set->elements = realloc(set->elements, set->capacity * sizeof(int));
    }

    set->elements[set->size++] = element;
}

void set_union(Set* dest, Set* src) {
    for (int i = 0; i < src->size; i++) {
        set_add(dest, src->elements[i]);
    }
}

int* set_to_sorted_array(Set* set, int* out_size) {
    // Sort the set
    for (int i = 0; i < set->size - 1; i++) {
        for (int j = 0; j < set->size - i - 1; j++) {
            if (set->elements[j] > set->elements[j + 1]) {
                int temp = set->elements[j];
                set->elements[j] = set->elements[j + 1];
                set->elements[j + 1] = temp;
            }
        }
    }

    *out_size = set->size;
    return set->elements;
}

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row sets
    Set** used_for_row = malloc(rows * sizeof(Set*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = create_set(1);
        set_add(used_for_row[i], i);
    }

    // Modulo PH operation
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Skip zero columns
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find non-zero row
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }

            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp;

            Set* temp_set = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_set;
        }

        int pivot = matrix[col][col + extra];
        
        // Assert pivot conditions
        if (col + extra < graphlen) {
            assert(abs(pivot) == 1 || abs(pivot) == PH - 1);
        } else {
            assert(abs(pivot) == 2 || abs(pivot) == PH - 2);
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            if (matrix[i][col + extra] != 0) {
                set_union(used_for_row[i], used_for_row[col]);

                if (col < graphlen) {
                    int scale = matrix[i][col + extra];
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * scale;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                        }
                    }
                }

                // Modulo operation
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] %= PH;
                }
            }
        }

        col++;
    }

    // Convert sets to sorted arrays
    int** result = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        int size;
        result[i] = set_to_sorted_array(used_for_row[i], &size);
        
        // Free set structure but not the array
        free(used_for_row[i]);
    }
    free(used_for_row);

    return result;
}
A few important notes: 1. This implementation includes a simple set-like data structure to mimic Python's set behavior. 2. Memory management is crucial in C. The function allocates memory that the caller should eventually free. 3. The function assumes the input matrix is correctly formatted and that `graphlen` is valid. 4. The implementation closely follows the Python logic, including the modulo operations and row elimination steps. Example usage might look like: 
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int main() {
    int rows = 3, cols = 4, graphlen = 2;
    int** matrix = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        matrix[i] = malloc(cols * sizeof(int));
        // Initialize matrix
    }

    int** result = rref(matrix, rows, cols, graphlen);

    // Use result, then free memory
    for (int i = 0; i < rows; i++) {
        free(matrix[i]);
        free(result[i]);
    }
    free(matrix);
    free(result);

    return 0;
}
This implementation provides a direct translation of the Python function to C, maintaining the same logic and behavior.

Extract Code

I extracted the following code from that output: 

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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

#define PH 16

typedef struct {
    int* elements;
    int size;
    int capacity;
} Set;

Set* create_set(int initial_capacity) {
    Set* set = malloc(sizeof(Set));
    set->elements = malloc(initial_capacity * sizeof(int));
    set->size = 0;
    set->capacity = initial_capacity;
    return set;
}

void set_add(Set* set, int element) {
    for (int i = 0; i < set->size; i++) {
        if (set->elements[i] == element) return;
    }

    if (set->size == set->capacity) {
        set->capacity *= 2;
        set->elements = realloc(set->elements, set->capacity * sizeof(int));
    }

    set->elements[set->size++] = element;
}

void set_union(Set* dest, Set* src) {
    for (int i = 0; i < src->size; i++) {
        set_add(dest, src->elements[i]);
    }
}

int* set_to_sorted_array(Set* set, int* out_size) {
    for (int i = 0; i < set->size - 1; i++) {
        for (int j = 0; j < set->size - i - 1; j++) {
            if (set->elements[j] > set->elements[j + 1]) {
                int temp = set->elements[j];
                set->elements[j] = set->elements[j + 1];
                set->elements[j + 1] = temp;
            }
        }
    }

    *out_size = set->size;
    return set->elements;
}

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    
    Set** used_for_row = malloc(rows * sizeof(Set*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = create_set(1);
        set_add(used_for_row[i], i);
    }

    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }

            if (other < col) {
                extra++;
                continue;
            }

            int* temp = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp;

            Set* temp_set = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_set;
        }

        int pivot = matrix[col][col + extra];
        
        if (col + extra < graphlen) {
            assert(abs(pivot) == 1 || abs(pivot) == PH - 1);
        } else {
            assert(abs(pivot) == 2 || abs(pivot) == PH - 2);
            pivot /= 2;
        }

        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            if (matrix[i][col + extra] != 0) {
                set_union(used_for_row[i], used_for_row[col]);

                if (col < graphlen) {
                    int scale = matrix[i][col + extra];
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * scale;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                        }
                    }
                }

                for (int j = 0; j < cols; j++) {
                    matrix[i][j] %= PH;
                }
            }
        }

        col++;
    }

    int** result = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        int size;
        result[i] = set_to_sorted_array(used_for_row[i], &size);
        
        free(used_for_row[i]);
    }
    free(used_for_row);

    return result;
}

Run Code Interpreter

Running the following program: 

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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

#define PH 16

typedef struct {
    int* elements;
    int size;
    int capacity;
} Set;

Set* create_set(int initial_capacity) {
    Set* set = malloc(sizeof(Set));
    set->elements = malloc(initial_capacity * sizeof(int));
    set->size = 0;
    set->capacity = initial_capacity;
    return set;
}

void set_add(Set* set, int element) {
    for (int i = 0; i < set->size; i++) {
        if (set->elements[i] == element) return;
    }

    if (set->size == set->capacity) {
        set->capacity *= 2;
        set->elements = realloc(set->elements, set->capacity * sizeof(int));
    }

    set->elements[set->size++] = element;
}

void set_union(Set* dest, Set* src) {
    for (int i = 0; i < src->size; i++) {
        set_add(dest, src->elements[i]);
    }
}

int* set_to_sorted_array(Set* set, int* out_size) {
    for (int i = 0; i < set->size - 1; i++) {
        for (int j = 0; j < set->size - i - 1; j++) {
            if (set->elements[j] > set->elements[j + 1]) {
                int temp = set->elements[j];
                set->elements[j] = set->elements[j + 1];
                set->elements[j + 1] = temp;
            }
        }
    }

    *out_size = set->size;
    return set->elements;
}

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    
    Set** used_for_row = malloc(rows * sizeof(Set*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = create_set(1);
        set_add(used_for_row[i], i);
    }

    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }

            if (other < col) {
                extra++;
                continue;
            }

            int* temp = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp;

            Set* temp_set = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_set;
        }

        int pivot = matrix[col][col + extra];
        
        if (col + extra < graphlen) {
            assert(abs(pivot) == 1 || abs(pivot) == PH - 1);
        } else {
            assert(abs(pivot) == 2 || abs(pivot) == PH - 2);
            pivot /= 2;
        }

        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        for (int i = 0; i < rows; i++) {
            if (i == col) continue;

            if (matrix[i][col + extra] != 0) {
                set_union(used_for_row[i], used_for_row[col]);

                if (col < graphlen) {
                    int scale = matrix[i][col + extra];
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] -= matrix[col][j] * scale;
                    }
                } else {
                    while (matrix[i][col + extra] != 0) {
                        for (int j = 0; j < cols; j++) {
                            matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                        }
                    }
                }

                for (int j = 0; j < cols; j++) {
                    matrix[i][j] %= PH;
                }
            }
        }

        col++;
    }

    int** result = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        int size;
        result[i] = set_to_sorted_array(used_for_row[i], &size);
        
        free(used_for_row[i]);
    }
    free(used_for_row);

    return result;
}



#include<stdio.h>
#include<stdlib.h>

int main() {

int arr0[] = {1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr1[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr2[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr3[] = {0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr4[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr5[] = {0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr6[] = {0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0};
int arr7[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, -30};
int arr8[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr9[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, -20};
int arr10[] = {1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr11[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr12[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr13[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -14};
int arr14[] = {0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr15[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, -30};
int arr16[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr17[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr18[] = {0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr19[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr20[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr21[] = {0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr22[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, -20};
int arr23[] = {0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr24[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr25[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr26[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr27[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr28[] = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr29[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr30[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr31[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr32[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, -10};
int arr33[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr34[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr35[] = {0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -9};
int arr36[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, -20};
int arr37[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, -40};
int arr38[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int* arr[] = {arr0, arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10, arr11, arr12, arr13, arr14, arr15, arr16, arr17, arr18, arr19, arr20, arr21, arr22, arr23, arr24, arr25, arr26, arr27, arr28, arr29, arr30, arr31, arr32, arr33, arr34, arr35, arr36, arr37, arr38};
int** got = rref(arr, 39, 49, 37);


int answer = got[3][0]+got[3][1]+got[3][2]+got[3][3]+got[3][4]+got[3][5]+got[3][6];
int expected = 146;
if (answer != expected) {
    printf("Wrong answer; got %d instead of %d.\n", answer, expected);
    exit(1);
}
printf("All tests passed\n");
}
And got the output: All tests passed

Substring Evaluation

Testing if the previous output contains the string All tests passed: True

Initial Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

LLM Generation

Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

Output

Here's a C implementation of the `rref` function based on the Python code you provided: 

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#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#define PH 16

// Helper function to find last non-zero index in a column
int find_last_nonzero(int** matrix, int rows, int col, int cols) {
    for (int i = rows - 1; i >= 0; i--) {
        if (matrix[i][col] != 0) {
            return i;
        }
    }
    return -1;
}

// Helper function to swap rows
void swap_rows(int** matrix, int row1, int row2, int cols, int* used_for_row, int graphlen) {
    int* temp = matrix[row1];
    matrix[row1] = matrix[row2];
    matrix[row2] = temp;

    int* temp_used = used_for_row[row1];
    used_for_row[row1] = used_for_row[row2];
    used_for_row[row2] = temp_used;
}

int** rref(int** matrix, int rows, int cols, int graphlen) {
    // Initialize used_for_row with singleton sets
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        for (int j = 0; j < rows; j++) {
            used_for_row[i][j] = -1;
        }
        used_for_row[i][0] = i;
    }

    // Modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    int extra = 0;
    int col = 0;

    while (col + extra < cols - 1 && col < rows) {
        // If pivot is zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find last non-zero row
            int other = find_last_nonzero(matrix, rows, col + extra, cols);
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            swap_rows(matrix, col, other, cols, used_for_row, graphlen);
        }

        int pivot = matrix[col][col + extra];
        
        // Adjust pivot based on graph length
        if (col + extra < graphlen) {
            if (!(abs(pivot) == 1 || abs(pivot) == PH - 1)) {
                // Handle error or return
                return NULL;
            }
        } else {
            if (!(abs(pivot) == 2 || abs(pivot) == PH - 2)) {
                // Handle error or return
                return NULL;
            }
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;
            
            // Combine used_for_row
            int used_idx = 0;
            while (used_for_row[col][used_idx] != -1) {
                int found = 0;
                for (int k = 0; used_for_row[i][k] != -1; k++) {
                    if (used_for_row[i][k] == used_for_row[col][used_idx]) {
                        found = 1;
                        break;
                    }
                }
                if (!found) {
                    // Add to used_for_row[i]
                    for (int k = 0; k < rows; k++) {
                        if (used_for_row[i][k] == -1) {
                            used_for_row[i][k] = used_for_row[col][used_idx];
                            break;
                        }
                    }
                }
                used_idx++;
                if (used_for_row[col][used_idx] == -1) break;
            }

            if (matrix[i][col + extra] == 0) continue;

            // Row reduction
            if (col + extra < graphlen) {
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                    matrix[i][j] %= PH;
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                    }
                }
            }
        }

        col++;
    }

    return used_for_row;
}
Key differences from the Python version: 1. Uses raw 2D arrays instead of NumPy arrays 2. Manual memory management with `malloc()` 3. Explicit modulo and arithmetic operations 4. Separate helper functions for row swapping and finding non-zero elements 5. Used -1 as a sentinel value for the end of `used_for_row` sets 6. More explicit row reduction logic Note: - This implementation assumes the caller will free the memory for `matrix` and `used_for_row` - Error handling is minimal (returns NULL on certain conditions) - The code maintains the core logic of the original Python function You would call this function like: 
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int rows = ..., cols = ..., graphlen = ...;
int** matrix = malloc(rows * sizeof(int*));
for (int i = 0; i < rows; i++) {
    matrix[i] = malloc(cols * sizeof(int));
    // Initialize matrix
}

int** result = rref(matrix, rows, cols, graphlen);
Remember to free the memory after use to prevent memory leaks.

Extract Code

I extracted the following code from that output: 

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#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#define PH 16

// Helper function to find last non-zero index in a column
int find_last_nonzero(int** matrix, int rows, int col, int cols) {
    for (int i = rows - 1; i >= 0; i--) {
        if (matrix[i][col] != 0) {
            return i;
        }
    }
    return -1;
}

// Helper function to swap rows
void swap_rows(int** matrix, int row1, int row2, int cols, int* used_for_row, int graphlen) {
    int* temp = matrix[row1];
    matrix[row1] = matrix[row2];
    matrix[row2] = temp;

    int* temp_used = used_for_row[row1];
    used_for_row[row1] = used_for_row[row2];
    used_for_row[row2] = temp_used;
}

int** rref(int** matrix, int rows, int cols, int graphlen) {
    // Initialize used_for_row with singleton sets
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        for (int j = 0; j < rows; j++) {
            used_for_row[i][j] = -1;
        }
        used_for_row[i][0] = i;
    }

    // Modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    int extra = 0;
    int col = 0;

    while (col + extra < cols - 1 && col < rows) {
        // If pivot is zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find last non-zero row
            int other = find_last_nonzero(matrix, rows, col + extra, cols);
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            swap_rows(matrix, col, other, cols, used_for_row, graphlen);
        }

        int pivot = matrix[col][col + extra];
        
        // Adjust pivot based on graph length
        if (col + extra < graphlen) {
            if (!(abs(pivot) == 1 || abs(pivot) == PH - 1)) {
                // Handle error or return
                return NULL;
            }
        } else {
            if (!(abs(pivot) == 2 || abs(pivot) == PH - 2)) {
                // Handle error or return
                return NULL;
            }
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;
            
            // Combine used_for_row
            int used_idx = 0;
            while (used_for_row[col][used_idx] != -1) {
                int found = 0;
                for (int k = 0; used_for_row[i][k] != -1; k++) {
                    if (used_for_row[i][k] == used_for_row[col][used_idx]) {
                        found = 1;
                        break;
                    }
                }
                if (!found) {
                    // Add to used_for_row[i]
                    for (int k = 0; k < rows; k++) {
                        if (used_for_row[i][k] == -1) {
                            used_for_row[i][k] = used_for_row[col][used_idx];
                            break;
                        }
                    }
                }
                used_idx++;
                if (used_for_row[col][used_idx] == -1) break;
            }

            if (matrix[i][col + extra] == 0) continue;

            // Row reduction
            if (col + extra < graphlen) {
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                    matrix[i][j] %= PH;
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                    }
                }
            }
        }

        col++;
    }

    return used_for_row;
}

Run Code Interpreter

Running the following program: 

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#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#define PH 16

// Helper function to find last non-zero index in a column
int find_last_nonzero(int** matrix, int rows, int col, int cols) {
    for (int i = rows - 1; i >= 0; i--) {
        if (matrix[i][col] != 0) {
            return i;
        }
    }
    return -1;
}

// Helper function to swap rows
void swap_rows(int** matrix, int row1, int row2, int cols, int* used_for_row, int graphlen) {
    int* temp = matrix[row1];
    matrix[row1] = matrix[row2];
    matrix[row2] = temp;

    int* temp_used = used_for_row[row1];
    used_for_row[row1] = used_for_row[row2];
    used_for_row[row2] = temp_used;
}

int** rref(int** matrix, int rows, int cols, int graphlen) {
    // Initialize used_for_row with singleton sets
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        for (int j = 0; j < rows; j++) {
            used_for_row[i][j] = -1;
        }
        used_for_row[i][0] = i;
    }

    // Modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    int extra = 0;
    int col = 0;

    while (col + extra < cols - 1 && col < rows) {
        // If pivot is zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }
            if (all_zero) {
                extra++;
                continue;
            }

            // Find last non-zero row
            int other = find_last_nonzero(matrix, rows, col + extra, cols);
            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            swap_rows(matrix, col, other, cols, used_for_row, graphlen);
        }

        int pivot = matrix[col][col + extra];
        
        // Adjust pivot based on graph length
        if (col + extra < graphlen) {
            if (!(abs(pivot) == 1 || abs(pivot) == PH - 1)) {
                // Handle error or return
                return NULL;
            }
        } else {
            if (!(abs(pivot) == 2 || abs(pivot) == PH - 2)) {
                // Handle error or return
                return NULL;
            }
            pivot /= 2;
        }

        // Scale row
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Eliminate other rows
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;
            
            // Combine used_for_row
            int used_idx = 0;
            while (used_for_row[col][used_idx] != -1) {
                int found = 0;
                for (int k = 0; used_for_row[i][k] != -1; k++) {
                    if (used_for_row[i][k] == used_for_row[col][used_idx]) {
                        found = 1;
                        break;
                    }
                }
                if (!found) {
                    // Add to used_for_row[i]
                    for (int k = 0; k < rows; k++) {
                        if (used_for_row[i][k] == -1) {
                            used_for_row[i][k] = used_for_row[col][used_idx];
                            break;
                        }
                    }
                }
                used_idx++;
                if (used_for_row[col][used_idx] == -1) break;
            }

            if (matrix[i][col + extra] == 0) continue;

            // Row reduction
            if (col + extra < graphlen) {
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                    matrix[i][j] %= PH;
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                    }
                }
            }
        }

        col++;
    }

    return used_for_row;
}



#include<stdio.h>
#include<stdlib.h>

int main() {

int arr0[] = {1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr1[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr2[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr3[] = {0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr4[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr5[] = {0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr6[] = {0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0};
int arr7[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, -30};
int arr8[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr9[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, -20};
int arr10[] = {1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr11[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr12[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr13[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -14};
int arr14[] = {0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr15[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, -30};
int arr16[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr17[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr18[] = {0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr19[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr20[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr21[] = {0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr22[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, -20};
int arr23[] = {0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr24[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr25[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr26[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr27[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr28[] = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr29[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr30[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr31[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr32[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, -10};
int arr33[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr34[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr35[] = {0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -9};
int arr36[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, -20};
int arr37[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, -40};
int arr38[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int* arr[] = {arr0, arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10, arr11, arr12, arr13, arr14, arr15, arr16, arr17, arr18, arr19, arr20, arr21, arr22, arr23, arr24, arr25, arr26, arr27, arr28, arr29, arr30, arr31, arr32, arr33, arr34, arr35, arr36, arr37, arr38};
int** got = rref(arr, 39, 49, 37);


int answer = got[3][0]+got[3][1]+got[3][2]+got[3][3]+got[3][4]+got[3][5]+got[3][6];
int expected = 146;
if (answer != expected) {
    printf("Wrong answer; got %d instead of %d.\n", answer, expected);
    exit(1);
}
printf("All tests passed\n");
}
And got the output: main.c: In function 'swap_rows': main.c:24:22: warning: initialization of 'int *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 24 | int* temp_used = used_for_row[row1]; | ^~~~~~~~~~~~ main.c:26:24: warning: assignment to 'int' from 'int *' makes integer from pointer without a cast [-Wint-conversion] 26 | used_for_row[row2] = temp_used; | ^ main.c: In function 'rref': main.c:74:49: warning: passing argument 5 of 'swap_rows' from incompatible pointer type [-Wincompatible-pointer-types] 74 | swap_rows(matrix, col, other, cols, used_for_row, graphlen); | ^~~~~~~~~~~~ | | | int ** main.c:19:65: note: expected 'int *' but argument is of type 'int **' 19 | void swap_rows(int** matrix, int row1, int row2, int cols, int* used_for_row, int graphlen) { | ~~~~~^~~~~~~~~~~~ main.sh: line 2: 16 Segmentation fault (core dumped) ./a.out

Substring Evaluation

Testing if the previous output contains the string All tests passed: False

Initial Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

LLM Generation

Query

Rewrite this function in C. You can assume that the input is a 2d matrix correctly formatted. Call it rref(int** matrix, int rows, int cols, int graphlen) where the size is matrix[rows][cols]. Return an int** of used_for_row. def rref(matrix, graphlen): PH = 16 extra = 0 col = 0 pivots = [] used_for_row = [set([i]) for i in range(matrix.shape[0])] matrix = matrix%PH while col+extra < matrix.shape[1]-1 and col < matrix.shape[0]: if matrix[col,col+extra] == 0: if np.all(matrix[:,col] == 0): extra += 1 continue other = np.argwhere(matrix[:,col+extra] != 0).flatten()[-1] if other < col: extra += 1 continue matrix[col], matrix[other] = list(matrix[other]), list(matrix[col]) used_for_row[col], used_for_row[other] = used_for_row[other], used_for_row[col] pivots.append(col+extra) pivot = matrix[col,col+extra] if col+extra < graphlen: assert np.abs(pivot) == 1 or np.abs(pivot) == PH-1 else: assert np.abs(pivot) == 2 or np.abs(pivot) == PH-2 pivot //= 2 matrix[col] *= pivot matrix[col] %= PH others = np.argwhere(matrix[:,col+extra]).flatten() for i in others: if i == col: continue used_for_row[i] |= used_for_row[col] if col < graphlen: matrix[i] -= matrix[col]*matrix[i,col+extra] else: while matrix[i,col+extra] != 0: matrix[i] = (matrix[i]-matrix[col])%PH matrix[i] %= PH col += 1 matrix = np.array(matrix)%PH return [sorted(x) for x in used_for_row]

Output

Here's a C implementation of the `rref` function: 

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#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int* pivots = malloc(rows * sizeof(int));
    int pivots_count = 0;

    // Initialize used_for_row
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row[i][1] = -1;  // Sentinel to mark end of set
    }

    // Modulo PH each matrix element
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Find an element that is not zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }

            if (all_zero) {
                extra++;
                continue;
            }

            // Find last non-zero element in column
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }

            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row sets
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
        }

        pivots[pivots_count++] = col + extra;
        int pivot = matrix[col][col + extra];

        // Assert pivot value based on graph length
        if (col + extra < graphlen) {
            if (abs(pivot) != 1 && abs(pivot) != PH - 1) {
                fprintf(stderr, "Assertion failed for graphlen\n");
                exit(1);
            }
        } else {
            if (abs(pivot) != 2 && abs(pivot) != PH - 2) {
                fprintf(stderr, "Assertion failed for non-graphlen\n");
                exit(1);
            }
            pivot /= 2;
        }

        // Multiply row by pivot and modulo
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Find indices of non-zero elements in column
        for (int i = 0; i < rows; i++) {
            if (i == col || matrix[i][col + extra] == 0) continue;

            // Merge used_for_row sets
            for (int j = 0; used_for_row[col][j] != -1; j++) {
                int found = 0;
                for (int k = 0; used_for_row[i][k] != -1; k++) {
                    if (used_for_row[i][k] == used_for_row[col][j]) {
                        found = 1;
                        break;
                    }
                }
                if (!found) {
                    int k = 0;
                    while (used_for_row[i][k] != -1) k++;
                    used_for_row[i][k] = used_for_row[col][j];
                    used_for_row[i][k + 1] = -1;
                }
            }

            // Subtract rows
            if (col < graphlen) {
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                    }
                }
            }

            // Modulo PH for each row
            for (int j = 0; j < cols; j++) {
                matrix[i][j] %= PH;
            }
        }

        col++;
    }

    // Sort each used_for_row set
    for (int i = 0; i < rows; i++) {
        int n = 0;
        while (used_for_row[i][n] != -1) n++;
        
        // Simple bubble sort
        for (int x = 0; x < n - 1; x++) {
            for (int y = 0; y < n - x - 1; y++) {
                if (used_for_row[i][y] > used_for_row[i][y + 1]) {
                    int temp = used_for_row[i][y];
                    used_for_row[i][y] = used_for_row[i][y + 1];
                    used_for_row[i][y + 1] = temp;
                }
            }
        }
    }

    // Cleanup pivots
    free(pivots);

    return used_for_row;
}
Key differences from the Python version: 1. Uses explicit memory management with `malloc` and `free`. 2. Uses `-1` as a sentinel to mark the end of sets in `used_for_row`. 3. Implements row operations and set merging manually. 4. Uses a simple bubble sort to sort `used_for_row` sets. 5. Handles matrix operations without NumPy. Note: This implementation assumes that the caller will manage the memory for `matrix` and `used_for_row`, including freeing the memory after use.

Extract Code

I extracted the following code from that output: 

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#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int* pivots = malloc(rows * sizeof(int));
    int pivots_count = 0;

    // Initialize used_for_row
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row[i][1] = -1;  // Sentinel to mark end of set
    }

    // Modulo PH each matrix element
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Find an element that is not zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }

            if (all_zero) {
                extra++;
                continue;
            }

            // Find last non-zero element in column
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }

            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row sets
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
        }

        pivots[pivots_count++] = col + extra;
        int pivot = matrix[col][col + extra];

        // Assert pivot value based on graph length
        if (col + extra < graphlen) {
            if (abs(pivot) != 1 && abs(pivot) != PH - 1) {
                fprintf(stderr, "Assertion failed for graphlen\n");
                exit(1);
            }
        } else {
            if (abs(pivot) != 2 && abs(pivot) != PH - 2) {
                fprintf(stderr, "Assertion failed for non-graphlen\n");
                exit(1);
            }
            pivot /= 2;
        }

        // Multiply row by pivot and modulo
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Find indices of non-zero elements in column
        for (int i = 0; i < rows; i++) {
            if (i == col || matrix[i][col + extra] == 0) continue;

            // Merge used_for_row sets
            for (int j = 0; used_for_row[col][j] != -1; j++) {
                int found = 0;
                for (int k = 0; used_for_row[i][k] != -1; k++) {
                    if (used_for_row[i][k] == used_for_row[col][j]) {
                        found = 1;
                        break;
                    }
                }
                if (!found) {
                    int k = 0;
                    while (used_for_row[i][k] != -1) k++;
                    used_for_row[i][k] = used_for_row[col][j];
                    used_for_row[i][k + 1] = -1;
                }
            }

            // Subtract rows
            if (col < graphlen) {
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                    }
                }
            }

            // Modulo PH for each row
            for (int j = 0; j < cols; j++) {
                matrix[i][j] %= PH;
            }
        }

        col++;
    }

    // Sort each used_for_row set
    for (int i = 0; i < rows; i++) {
        int n = 0;
        while (used_for_row[i][n] != -1) n++;
        
        // Simple bubble sort
        for (int x = 0; x < n - 1; x++) {
            for (int y = 0; y < n - x - 1; y++) {
                if (used_for_row[i][y] > used_for_row[i][y + 1]) {
                    int temp = used_for_row[i][y];
                    used_for_row[i][y] = used_for_row[i][y + 1];
                    used_for_row[i][y + 1] = temp;
                }
            }
        }
    }

    // Cleanup pivots
    free(pivots);

    return used_for_row;
}

Run Code Interpreter

Running the following program: 

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#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

#define PH 16

int** rref(int** matrix, int rows, int cols, int graphlen) {
    int extra = 0;
    int col = 0;
    int* pivots = malloc(rows * sizeof(int));
    int pivots_count = 0;

    // Initialize used_for_row
    int** used_for_row = malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row[i][1] = -1;  // Sentinel to mark end of set
    }

    // Modulo PH each matrix element
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] %= PH;
        }
    }

    while (col + extra < cols - 1 && col < rows) {
        // Find an element that is not zero
        if (matrix[col][col + extra] == 0) {
            // Check if entire column is zero
            bool all_zero = true;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zero = false;
                    break;
                }
            }

            if (all_zero) {
                extra++;
                continue;
            }

            // Find last non-zero element in column
            int other = -1;
            for (int i = rows - 1; i >= 0; i--) {
                if (matrix[i][col + extra] != 0) {
                    other = i;
                    break;
                }
            }

            if (other < col) {
                extra++;
                continue;
            }

            // Swap rows
            int* temp_row = matrix[col];
            matrix[col] = matrix[other];
            matrix[other] = temp_row;

            // Swap used_for_row sets
            int* temp_used = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_used;
        }

        pivots[pivots_count++] = col + extra;
        int pivot = matrix[col][col + extra];

        // Assert pivot value based on graph length
        if (col + extra < graphlen) {
            if (abs(pivot) != 1 && abs(pivot) != PH - 1) {
                fprintf(stderr, "Assertion failed for graphlen\n");
                exit(1);
            }
        } else {
            if (abs(pivot) != 2 && abs(pivot) != PH - 2) {
                fprintf(stderr, "Assertion failed for non-graphlen\n");
                exit(1);
            }
            pivot /= 2;
        }

        // Multiply row by pivot and modulo
        for (int j = 0; j < cols; j++) {
            matrix[col][j] *= pivot;
            matrix[col][j] %= PH;
        }

        // Find indices of non-zero elements in column
        for (int i = 0; i < rows; i++) {
            if (i == col || matrix[i][col + extra] == 0) continue;

            // Merge used_for_row sets
            for (int j = 0; used_for_row[col][j] != -1; j++) {
                int found = 0;
                for (int k = 0; used_for_row[i][k] != -1; k++) {
                    if (used_for_row[i][k] == used_for_row[col][j]) {
                        found = 1;
                        break;
                    }
                }
                if (!found) {
                    int k = 0;
                    while (used_for_row[i][k] != -1) k++;
                    used_for_row[i][k] = used_for_row[col][j];
                    used_for_row[i][k + 1] = -1;
                }
            }

            // Subtract rows
            if (col < graphlen) {
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] -= matrix[col][j] * matrix[i][col + extra];
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j] + PH) % PH;
                    }
                }
            }

            // Modulo PH for each row
            for (int j = 0; j < cols; j++) {
                matrix[i][j] %= PH;
            }
        }

        col++;
    }

    // Sort each used_for_row set
    for (int i = 0; i < rows; i++) {
        int n = 0;
        while (used_for_row[i][n] != -1) n++;
        
        // Simple bubble sort
        for (int x = 0; x < n - 1; x++) {
            for (int y = 0; y < n - x - 1; y++) {
                if (used_for_row[i][y] > used_for_row[i][y + 1]) {
                    int temp = used_for_row[i][y];
                    used_for_row[i][y] = used_for_row[i][y + 1];
                    used_for_row[i][y + 1] = temp;
                }
            }
        }
    }

    // Cleanup pivots
    free(pivots);

    return used_for_row;
}



#include<stdio.h>
#include<stdlib.h>

int main() {

int arr0[] = {1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr1[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr2[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr3[] = {0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, -20};
int arr4[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr5[] = {0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr6[] = {0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 0};
int arr7[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, -30};
int arr8[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr9[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, -20};
int arr10[] = {1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
int arr11[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr12[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr13[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -14};
int arr14[] = {0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr15[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, -30};
int arr16[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr17[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr18[] = {0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr19[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr20[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr21[] = {0, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr22[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, -20};
int arr23[] = {0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10};
int arr24[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr25[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr26[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr27[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr28[] = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr29[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr30[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int arr31[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr32[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, -10};
int arr33[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -13};
int arr34[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -11};
int arr35[] = {0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -9};
int arr36[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, -20};
int arr37[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, -40};
int arr38[] = {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int* arr[] = {arr0, arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10, arr11, arr12, arr13, arr14, arr15, arr16, arr17, arr18, arr19, arr20, arr21, arr22, arr23, arr24, arr25, arr26, arr27, arr28, arr29, arr30, arr31, arr32, arr33, arr34, arr35, arr36, arr37, arr38};
int** got = rref(arr, 39, 49, 37);


int answer = got[3][0]+got[3][1]+got[3][2]+got[3][3]+got[3][4]+got[3][5]+got[3][6];
int expected = 146;
if (answer != expected) {
    printf("Wrong answer; got %d instead of %d.\n", answer, expected);
    exit(1);
}
printf("All tests passed\n");
}
And got the output: Wrong answer; got 66 instead of 146.

Substring Evaluation

Testing if the previous output contains the string All tests passed: False