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

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

int** rref(int** matrix, int rows, int cols, int graphlen) {
    const int PH = 16;
    
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row
    int** used_for_row = (int**)malloc(rows * sizeof(int*));
    int* used_for_row_sizes = (int*)malloc(rows * sizeof(int));
    
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = (int*)malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row_sizes[i] = 1;
    }
    
    // Take matrix modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;
        }
    }
    
    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            // Check if the entire column is zero
            int all_zeros = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zeros = 0;
                    break;
                }
            }
            
            if (all_zeros) {
                extra += 1;
                continue;
            }
            
            // Find the last non-zero entry in the 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 += 1;
                continue;
            }
            
            // Swap rows
            for (int j = 0; j < cols; j++) {
                int temp = matrix[col][j];
                matrix[col][j] = matrix[other][j];
                matrix[other][j] = temp;
            }
            
            // Swap used_for_row
            int* temp_arr = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_arr;
            
            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;
        }
        
        // Process 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;
        }
        
        // Multiply row by pivot
        for (int j = 0; j < cols; j++) {
            matrix[col][j] = (matrix[col][j] * pivot) % PH;
        }
        
        // Find rows with non-zero in current column
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;
            
            if (matrix[i][col + extra] != 0) {
                // Union operation: merge used_for_row[col] into used_for_row[i]
                int new_size = used_for_row_sizes[i];
                for (int k = 0; k < used_for_row_sizes[col]; k++) {
                    int is_in = 0;
                    for (int l = 0; l < used_for_row_sizes[i]; l++) {
                        if (used_for_row[i][l] == used_for_row[col][k]) {
                            is_in = 1;
                            break;
                        }
                    }
                    if (!is_in) {
                        used_for_row[i][new_size++] = used_for_row[col][k];
                    }
                }
                used_for_row_sizes[i] = new_size;
                
                if (col < graphlen) {
                    int factor = matrix[i][col + extra];
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - (matrix[col][j] * factor) % PH) % PH;
                        if (matrix[i][j] < 0) 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;
                            if (matrix[i][j] < 0) matrix[i][j] += PH;
                        }
                    }
                }
            }
        }
        
        col += 1;
    }
    
    // Sort used_for_row arrays
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < used_for_row_sizes[i] - 1; j++) {
            for (int k = j + 1; k < used_for_row_sizes[i]; k++) {
                if (used_for_row[i][j] > used_for_row[i][k]) {
                    int temp = used_for_row[i][j];
                    used_for_row[i][j] = used_for_row[i][k];
                    used_for_row[i][k] = temp;
                }
            }
        }
    }
    
    // We don't free used_for_row_sizes because the caller needs to know the size of each array
    free(used_for_row_sizes);
    
    return used_for_row;
}
This C implementation replicates the functionality of the Python code. It performs row reduction on the input matrix and maintains a record of which rows were used to create each row in the reduced form. Key notes: 1. The function returns an array of arrays where each inner array represents the set of row indices used to form that row. 2. We allocate each used_for_row[i] with enough space to potentially hold all row indices. 3. The set operations from Python are implemented using arrays and linear searches. 4. Memory management is handled properly, with the caller responsible for freeing the returned array.

Extract Code

I extracted the following code from that output: 

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

int** rref(int** matrix, int rows, int cols, int graphlen) {
    const int PH = 16;
    
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row
    int** used_for_row = (int**)malloc(rows * sizeof(int*));
    int* used_for_row_sizes = (int*)malloc(rows * sizeof(int));
    
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = (int*)malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row_sizes[i] = 1;
    }
    
    // Take matrix modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;
        }
    }
    
    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            // Check if the entire column is zero
            int all_zeros = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zeros = 0;
                    break;
                }
            }
            
            if (all_zeros) {
                extra += 1;
                continue;
            }
            
            // Find the last non-zero entry in the 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 += 1;
                continue;
            }
            
            // Swap rows
            for (int j = 0; j < cols; j++) {
                int temp = matrix[col][j];
                matrix[col][j] = matrix[other][j];
                matrix[other][j] = temp;
            }
            
            // Swap used_for_row
            int* temp_arr = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_arr;
            
            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;
        }
        
        // Process 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;
        }
        
        // Multiply row by pivot
        for (int j = 0; j < cols; j++) {
            matrix[col][j] = (matrix[col][j] * pivot) % PH;
        }
        
        // Find rows with non-zero in current column
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;
            
            if (matrix[i][col + extra] != 0) {
                // Union operation: merge used_for_row[col] into used_for_row[i]
                int new_size = used_for_row_sizes[i];
                for (int k = 0; k < used_for_row_sizes[col]; k++) {
                    int is_in = 0;
                    for (int l = 0; l < used_for_row_sizes[i]; l++) {
                        if (used_for_row[i][l] == used_for_row[col][k]) {
                            is_in = 1;
                            break;
                        }
                    }
                    if (!is_in) {
                        used_for_row[i][new_size++] = used_for_row[col][k];
                    }
                }
                used_for_row_sizes[i] = new_size;
                
                if (col < graphlen) {
                    int factor = matrix[i][col + extra];
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - (matrix[col][j] * factor) % PH) % PH;
                        if (matrix[i][j] < 0) 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;
                            if (matrix[i][j] < 0) matrix[i][j] += PH;
                        }
                    }
                }
            }
        }
        
        col += 1;
    }
    
    // Sort used_for_row arrays
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < used_for_row_sizes[i] - 1; j++) {
            for (int k = j + 1; k < used_for_row_sizes[i]; k++) {
                if (used_for_row[i][j] > used_for_row[i][k]) {
                    int temp = used_for_row[i][j];
                    used_for_row[i][j] = used_for_row[i][k];
                    used_for_row[i][k] = temp;
                }
            }
        }
    }
    
    // We don't free used_for_row_sizes because the caller needs to know the size of each 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 <assert.h>
#include <string.h>

int** rref(int** matrix, int rows, int cols, int graphlen) {
    const int PH = 16;
    
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row
    int** used_for_row = (int**)malloc(rows * sizeof(int*));
    int* used_for_row_sizes = (int*)malloc(rows * sizeof(int));
    
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = (int*)malloc(rows * sizeof(int));
        used_for_row[i][0] = i;
        used_for_row_sizes[i] = 1;
    }
    
    // Take matrix modulo PH
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;
        }
    }
    
    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            // Check if the entire column is zero
            int all_zeros = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    all_zeros = 0;
                    break;
                }
            }
            
            if (all_zeros) {
                extra += 1;
                continue;
            }
            
            // Find the last non-zero entry in the 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 += 1;
                continue;
            }
            
            // Swap rows
            for (int j = 0; j < cols; j++) {
                int temp = matrix[col][j];
                matrix[col][j] = matrix[other][j];
                matrix[other][j] = temp;
            }
            
            // Swap used_for_row
            int* temp_arr = used_for_row[col];
            used_for_row[col] = used_for_row[other];
            used_for_row[other] = temp_arr;
            
            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;
        }
        
        // Process 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;
        }
        
        // Multiply row by pivot
        for (int j = 0; j < cols; j++) {
            matrix[col][j] = (matrix[col][j] * pivot) % PH;
        }
        
        // Find rows with non-zero in current column
        for (int i = 0; i < rows; i++) {
            if (i == col) continue;
            
            if (matrix[i][col + extra] != 0) {
                // Union operation: merge used_for_row[col] into used_for_row[i]
                int new_size = used_for_row_sizes[i];
                for (int k = 0; k < used_for_row_sizes[col]; k++) {
                    int is_in = 0;
                    for (int l = 0; l < used_for_row_sizes[i]; l++) {
                        if (used_for_row[i][l] == used_for_row[col][k]) {
                            is_in = 1;
                            break;
                        }
                    }
                    if (!is_in) {
                        used_for_row[i][new_size++] = used_for_row[col][k];
                    }
                }
                used_for_row_sizes[i] = new_size;
                
                if (col < graphlen) {
                    int factor = matrix[i][col + extra];
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - (matrix[col][j] * factor) % PH) % PH;
                        if (matrix[i][j] < 0) 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;
                            if (matrix[i][j] < 0) matrix[i][j] += PH;
                        }
                    }
                }
            }
        }
        
        col += 1;
    }
    
    // Sort used_for_row arrays
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < used_for_row_sizes[i] - 1; j++) {
            for (int k = j + 1; k < used_for_row_sizes[i]; k++) {
                if (used_for_row[i][j] > used_for_row[i][k]) {
                    int temp = used_for_row[i][j];
                    used_for_row[i][j] = used_for_row[i][k];
                    used_for_row[i][k] = temp;
                }
            }
        }
    }
    
    // We don't free used_for_row_sizes because the caller needs to know the size of each 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: 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

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

int** rref(int** matrix, int rows, int cols, int graphlen) {
    const int PH = 16;
    
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row
    int** used_for_row = (int**)malloc(rows * sizeof(int*));
    int* used_for_row_size = (int*)malloc(rows * sizeof(int));
    
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = (int*)malloc(rows * sizeof(int)); // Maximum possible size
        used_for_row[i][0] = i;
        used_for_row_size[i] = 1;
    }
    
    // Apply modulo PH to the entire matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;  // Ensure positive modulo
        }
    }
    
    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            // Check if the entire column is zero
            int is_col_all_zero = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    is_col_all_zero = 0;
                    break;
                }
            }
            
            if (is_col_all_zero) {
                extra++;
                continue;
            }
            
            // Find the last non-zero element in the 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
            for (int j = 0; j < cols; j++) {
                int temp = matrix[col][j];
                matrix[col][j] = matrix[other][j];
                matrix[other][j] = temp;
            }
            
            // Swap used_for_row
            int* temp_used = used_for_row[col];
            int temp_size = used_for_row_size[col];
            used_for_row[col] = used_for_row[other];
            used_for_row_size[col] = used_for_row_size[other];
            used_for_row[other] = temp_used;
            used_for_row_size[other] = temp_size;
        }
        
        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;
        }
        
        // Multiply row by pivot
        for (int j = 0; j < cols; j++) {
            matrix[col][j] = (matrix[col][j] * pivot) % PH;
        }
        
        // Process other rows
        for (int i = 0; i < rows; i++) {
            if (i == col || matrix[i][col + extra] == 0) continue;
            
            // Merge used_for_row[col] into used_for_row[i]
            for (int k = 0; k < used_for_row_size[col]; k++) {
                int value = used_for_row[col][k];
                int exists = 0;
                for (int l = 0; l < used_for_row_size[i]; l++) {
                    if (used_for_row[i][l] == value) {
                        exists = 1;
                        break;
                    }
                }
                if (!exists) {
                    used_for_row[i][used_for_row_size[i]++] = value;
                }
            }
            
            if (col < graphlen) {
                int multiplier = matrix[i][col + extra];
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] = (matrix[i][j] - multiplier * matrix[col][j]) % PH;
                    if (matrix[i][j] < 0) matrix[i][j] += PH;  // Ensure positive modulo
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        if (matrix[i][j] < 0) matrix[i][j] += PH;  // Ensure positive modulo
                    }
                }
            }
        }
        
        col++;
    }
    
    // Apply modulo PH to the entire matrix again
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;
        }
    }
    
    // Sort the values in each used_for_row array
    for (int i = 0; i < rows; i++) {
        // Bubble sort
        for (int j = 0; j < used_for_row_size[i] - 1; j++) {
            for (int k = 0; k < used_for_row_size[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;
                }
            }
        }
    }
    
    // Create final result with exact sizes
    int** result = (int**)malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        result[i] = (int*)malloc((used_for_row_size[i] + 1) * sizeof(int)); // +1 for size
        result[i][0] = used_for_row_size[i]; // Store size at index 0
        for (int j = 0; j < used_for_row_size[i]; j++) {
            result[i][j + 1] = used_for_row[i][j];
        }
        free(used_for_row[i]);
    }
    
    free(used_for_row);
    free(used_for_row_size);
    
    return result;
}
I've translated the Python function to C, making several adaptations: 1. Each `used_for_row[i]` array now includes its size at index 0, so `used_for_row[i][0]` is the count of elements, followed by the actual values. 2. The modulo operations ensure positive values by adding PH when needed. 3. The set union operation (|=) has been implemented by checking for existence before adding elements. 4. Memory is properly allocated and freed throughout the function. 5. The values in each used_for_row array are sorted using bubble sort to match the Python output. Note that the caller is responsible for freeing the returned 2D array when done with it.

Extract Code

I extracted the following code from that output: 

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

int** rref(int** matrix, int rows, int cols, int graphlen) {
    const int PH = 16;
    
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row
    int** used_for_row = (int**)malloc(rows * sizeof(int*));
    int* used_for_row_size = (int*)malloc(rows * sizeof(int));
    
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = (int*)malloc(rows * sizeof(int)); // Maximum possible size
        used_for_row[i][0] = i;
        used_for_row_size[i] = 1;
    }
    
    // Apply modulo PH to the entire matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;  // Ensure positive modulo
        }
    }
    
    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            // Check if the entire column is zero
            int is_col_all_zero = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    is_col_all_zero = 0;
                    break;
                }
            }
            
            if (is_col_all_zero) {
                extra++;
                continue;
            }
            
            // Find the last non-zero element in the 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
            for (int j = 0; j < cols; j++) {
                int temp = matrix[col][j];
                matrix[col][j] = matrix[other][j];
                matrix[other][j] = temp;
            }
            
            // Swap used_for_row
            int* temp_used = used_for_row[col];
            int temp_size = used_for_row_size[col];
            used_for_row[col] = used_for_row[other];
            used_for_row_size[col] = used_for_row_size[other];
            used_for_row[other] = temp_used;
            used_for_row_size[other] = temp_size;
        }
        
        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;
        }
        
        // Multiply row by pivot
        for (int j = 0; j < cols; j++) {
            matrix[col][j] = (matrix[col][j] * pivot) % PH;
        }
        
        // Process other rows
        for (int i = 0; i < rows; i++) {
            if (i == col || matrix[i][col + extra] == 0) continue;
            
            // Merge used_for_row[col] into used_for_row[i]
            for (int k = 0; k < used_for_row_size[col]; k++) {
                int value = used_for_row[col][k];
                int exists = 0;
                for (int l = 0; l < used_for_row_size[i]; l++) {
                    if (used_for_row[i][l] == value) {
                        exists = 1;
                        break;
                    }
                }
                if (!exists) {
                    used_for_row[i][used_for_row_size[i]++] = value;
                }
            }
            
            if (col < graphlen) {
                int multiplier = matrix[i][col + extra];
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] = (matrix[i][j] - multiplier * matrix[col][j]) % PH;
                    if (matrix[i][j] < 0) matrix[i][j] += PH;  // Ensure positive modulo
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        if (matrix[i][j] < 0) matrix[i][j] += PH;  // Ensure positive modulo
                    }
                }
            }
        }
        
        col++;
    }
    
    // Apply modulo PH to the entire matrix again
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;
        }
    }
    
    // Sort the values in each used_for_row array
    for (int i = 0; i < rows; i++) {
        // Bubble sort
        for (int j = 0; j < used_for_row_size[i] - 1; j++) {
            for (int k = 0; k < used_for_row_size[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;
                }
            }
        }
    }
    
    // Create final result with exact sizes
    int** result = (int**)malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        result[i] = (int*)malloc((used_for_row_size[i] + 1) * sizeof(int)); // +1 for size
        result[i][0] = used_for_row_size[i]; // Store size at index 0
        for (int j = 0; j < used_for_row_size[i]; j++) {
            result[i][j + 1] = used_for_row[i][j];
        }
        free(used_for_row[i]);
    }
    
    free(used_for_row);
    free(used_for_row_size);
    
    return result;
}

Run Code Interpreter

Running the following program: 

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

int** rref(int** matrix, int rows, int cols, int graphlen) {
    const int PH = 16;
    
    int extra = 0;
    int col = 0;
    
    // Initialize used_for_row
    int** used_for_row = (int**)malloc(rows * sizeof(int*));
    int* used_for_row_size = (int*)malloc(rows * sizeof(int));
    
    for (int i = 0; i < rows; i++) {
        used_for_row[i] = (int*)malloc(rows * sizeof(int)); // Maximum possible size
        used_for_row[i][0] = i;
        used_for_row_size[i] = 1;
    }
    
    // Apply modulo PH to the entire matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;  // Ensure positive modulo
        }
    }
    
    while (col + extra < cols - 1 && col < rows) {
        if (matrix[col][col + extra] == 0) {
            // Check if the entire column is zero
            int is_col_all_zero = 1;
            for (int i = 0; i < rows; i++) {
                if (matrix[i][col + extra] != 0) {
                    is_col_all_zero = 0;
                    break;
                }
            }
            
            if (is_col_all_zero) {
                extra++;
                continue;
            }
            
            // Find the last non-zero element in the 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
            for (int j = 0; j < cols; j++) {
                int temp = matrix[col][j];
                matrix[col][j] = matrix[other][j];
                matrix[other][j] = temp;
            }
            
            // Swap used_for_row
            int* temp_used = used_for_row[col];
            int temp_size = used_for_row_size[col];
            used_for_row[col] = used_for_row[other];
            used_for_row_size[col] = used_for_row_size[other];
            used_for_row[other] = temp_used;
            used_for_row_size[other] = temp_size;
        }
        
        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;
        }
        
        // Multiply row by pivot
        for (int j = 0; j < cols; j++) {
            matrix[col][j] = (matrix[col][j] * pivot) % PH;
        }
        
        // Process other rows
        for (int i = 0; i < rows; i++) {
            if (i == col || matrix[i][col + extra] == 0) continue;
            
            // Merge used_for_row[col] into used_for_row[i]
            for (int k = 0; k < used_for_row_size[col]; k++) {
                int value = used_for_row[col][k];
                int exists = 0;
                for (int l = 0; l < used_for_row_size[i]; l++) {
                    if (used_for_row[i][l] == value) {
                        exists = 1;
                        break;
                    }
                }
                if (!exists) {
                    used_for_row[i][used_for_row_size[i]++] = value;
                }
            }
            
            if (col < graphlen) {
                int multiplier = matrix[i][col + extra];
                for (int j = 0; j < cols; j++) {
                    matrix[i][j] = (matrix[i][j] - multiplier * matrix[col][j]) % PH;
                    if (matrix[i][j] < 0) matrix[i][j] += PH;  // Ensure positive modulo
                }
            } else {
                while (matrix[i][col + extra] != 0) {
                    for (int j = 0; j < cols; j++) {
                        matrix[i][j] = (matrix[i][j] - matrix[col][j]) % PH;
                        if (matrix[i][j] < 0) matrix[i][j] += PH;  // Ensure positive modulo
                    }
                }
            }
        }
        
        col++;
    }
    
    // Apply modulo PH to the entire matrix again
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            matrix[i][j] = ((matrix[i][j] % PH) + PH) % PH;
        }
    }
    
    // Sort the values in each used_for_row array
    for (int i = 0; i < rows; i++) {
        // Bubble sort
        for (int j = 0; j < used_for_row_size[i] - 1; j++) {
            for (int k = 0; k < used_for_row_size[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;
                }
            }
        }
    }
    
    // Create final result with exact sizes
    int** result = (int**)malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        result[i] = (int*)malloc((used_for_row_size[i] + 1) * sizeof(int)); // +1 for size
        result[i][0] = used_for_row_size[i]; // Store size at index 0
        for (int j = 0; j < used_for_row_size[i]; j++) {
            result[i][j + 1] = used_for_row[i][j];
        }
        free(used_for_row[i]);
    }
    
    free(used_for_row);
    free(used_for_row_size);
    
    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: Wrong answer; got 115 instead of 146.

Substring Evaluation

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