A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
## Plan for Counting Unholy 8x8 Matrices **1. Data Representation:** - An 8x8 binary matrix will be represented using 8 unsigned longs (64 bits each). Each unsigned long represents a row. - We can also use a single unsigned long to represent two rows at once, which will be useful in our dynamic programming approach. **2. `is_unholy` Function:** - This function takes an array of 8 unsigned longs (or a portion of it representing the rows built so far) and checks if the matrix represented so far is unholy. - It iterates through each '1' in the matrix. - For each '1', it checks its 4 neighbors (up, down, left, right) using bitwise operations (shifts and masks). - If any '1' has no '1' neighbors, the matrix is holy (and the function returns 0). - If all '1's have at least one '1' neighbor, the matrix is unholy (and the function returns 1). **3. Dynamic Programming:** - `count_unholy(int rows, unsigned long prev_row, unsigned long current_row)`: This recursive function will count the number of unholy matrices. - `rows`: Number of rows already processed. - `prev_row`: The row before the current row. - `current_row`: The current row being processed. - Base case: If `rows == 8`, check if the completed matrix is unholy using `is_unholy`. Return 1 if unholy, 0 if holy. - Recursive step: - Iterate through all possible next two rows (2^16 combinations). - For each combination: - Check if adding these two rows maintains the "unholy" property so far. - Recursively call `count_unholy(rows + 2, current_row, next_row)` where `next_row` is the second of the two new rows. - Sum up the results of the recursive calls. - Memoization (optional): Store the results of `count_unholy` for given `rows`, `prev_row`, and `current_row` to avoid redundant computations. This would require a large 3D array or a hash table. **4. Main Function:** - Initialize the count to 0. - Iterate through all possible first two rows (2^16 combinations). - For each combination, call `count_unholy(2, first_row, second_row)` and add the result to the count. - Print the final count. ## C Implementation
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | #include <stdio.h> #include <stdint.h> // Checks if a partially filled matrix (up to 'rows' rows) is unholy int is_unholy(uint64_t matrix[], int rows) { for (int i = 0; i < rows; i++) { for (int j = 0; j < 8; j++) { if ((matrix[i] >> j) & 1) { // If there's a 1 int has_neighbor = 0; if (i > 0 && ((matrix[i - 1] >> j) & 1)) has_neighbor = 1; // Up if (i < rows - 1 && ((matrix[i + 1] >> j) & 1)) has_neighbor = 1; // Down if (j > 0 && ((matrix[i] >> (j - 1)) & 1)) has_neighbor = 1; // Left if (j < 7 && ((matrix[i] >> (j + 1)) & 1)) has_neighbor = 1; // Right if (!has_neighbor) return 0; // Holy } } } return 1; // Unholy so far } uint64_t count_unholy(uint64_t matrix[], int rows) { if (rows == 8) { return is_unholy(matrix, 8); } uint64_t count = 0; for (uint64_t next_rows = 0; next_rows < (1ULL << 16); next_rows++) { matrix[rows] = next_rows & 0xFF; // lower 8 bits matrix[rows+1] = next_rows >> 8; // upper 8 bits if (is_unholy(matrix, rows + 2)) { count += count_unholy(matrix, rows + 2); } } return count; } int main() { uint64_t matrix[8]; uint64_t total_unholy = 0; for (uint64_t first_rows = 0; first_rows < (1ULL << 16); first_rows++) { matrix[0] = first_rows & 0xFF; matrix[1] = first_rows >> 8; total_unholy += count_unholy(matrix, 2); } printf("Total unholy 8x8 matrices: %lu\n", total_unholy); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | #include <stdio.h> #include <stdint.h> // Checks if a partially filled matrix (up to 'rows' rows) is unholy int is_unholy(uint64_t matrix[], int rows) { for (int i = 0; i < rows; i++) { for (int j = 0; j < 8; j++) { if ((matrix[i] >> j) & 1) { // If there's a 1 int has_neighbor = 0; if (i > 0 && ((matrix[i - 1] >> j) & 1)) has_neighbor = 1; // Up if (i < rows - 1 && ((matrix[i + 1] >> j) & 1)) has_neighbor = 1; // Down if (j > 0 && ((matrix[i] >> (j - 1)) & 1)) has_neighbor = 1; // Left if (j < 7 && ((matrix[i] >> (j + 1)) & 1)) has_neighbor = 1; // Right if (!has_neighbor) return 0; // Holy } } } return 1; // Unholy so far } uint64_t count_unholy(uint64_t matrix[], int rows) { if (rows == 8) { return is_unholy(matrix, 8); } uint64_t count = 0; for (uint64_t next_rows = 0; next_rows < (1ULL << 16); next_rows++) { matrix[rows] = next_rows & 0xFF; // lower 8 bits matrix[rows+1] = next_rows >> 8; // upper 8 bits if (is_unholy(matrix, rows + 2)) { count += count_unholy(matrix, rows + 2); } } return count; } int main() { uint64_t matrix[8]; uint64_t total_unholy = 0; for (uint64_t first_rows = 0; first_rows < (1ULL << 16); first_rows++) { matrix[0] = first_rows & 0xFF; matrix[1] = first_rows >> 8; total_unholy += count_unholy(matrix, 2); } printf("Total unholy 8x8 matrices: %lu\n", total_unholy); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | #include <stdio.h> #include <stdint.h> // Checks if a partially filled matrix (up to 'rows' rows) is unholy int is_unholy(uint64_t matrix[], int rows) { for (int i = 0; i < rows; i++) { for (int j = 0; j < 8; j++) { if ((matrix[i] >> j) & 1) { // If there's a 1 int has_neighbor = 0; if (i > 0 && ((matrix[i - 1] >> j) & 1)) has_neighbor = 1; // Up if (i < rows - 1 && ((matrix[i + 1] >> j) & 1)) has_neighbor = 1; // Down if (j > 0 && ((matrix[i] >> (j - 1)) & 1)) has_neighbor = 1; // Left if (j < 7 && ((matrix[i] >> (j + 1)) & 1)) has_neighbor = 1; // Right if (!has_neighbor) return 0; // Holy } } } return 1; // Unholy so far } uint64_t count_unholy(uint64_t matrix[], int rows) { if (rows == 8) { return is_unholy(matrix, 8); } uint64_t count = 0; for (uint64_t next_rows = 0; next_rows < (1ULL << 16); next_rows++) { matrix[rows] = next_rows & 0xFF; // lower 8 bits matrix[rows+1] = next_rows >> 8; // upper 8 bits if (is_unholy(matrix, rows + 2)) { count += count_unholy(matrix, rows + 2); } } return count; } int main() { uint64_t matrix[8]; uint64_t total_unholy = 0; for (uint64_t first_rows = 0; first_rows < (1ULL << 16); first_rows++) { matrix[0] = first_rows & 0xFF; matrix[1] = first_rows >> 8; total_unholy += count_unholy(matrix, 2); } printf("Total unholy 8x8 matrices: %lu\n", total_unholy); return 0; } |
Timeout: function took too long to complete
Testing if the previous output contains the string 1121231537486377866
: False
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
## Plan for Counting Unholy 8x8 Matrices This plan outlines the approach using dynamic programming and bit manipulation to count unholy 8x8 matrices. **1. Data Representation:** - An 8x8 matrix will be represented using 8 unsigned longs (64-bit), each representing a row. - Each bit in an unsigned long corresponds to a cell in the row (1 for a '1', 0 for a '0'). **2. `is_unholy` Function:** - This function will take two rows (unsigned longs) as input. - It will check if any '1' in the first row is isolated, considering its neighbors in the same row and the second row. - It will use bitwise operations (shifts, AND, OR) for efficient checking. - Returns 1 if unholy, 0 if holy (contains isolated 1s). **3. Dynamic Programming:** - `dp[i][prev_row][curr_row]` will store the number of unholy i x 8 matrices ending with `prev_row` and `curr_row`. - Base case: `dp[2][prev_row][curr_row]` will be 1 if the combination of `prev_row` and `curr_row` forms an unholy 2x8 matrix, and 0 otherwise. - Recursive step: Iterate through all possible next rows (`next_prev_row`, `next_curr_row`). If the combination of `curr_row` and `next_prev_row` and `next_curr_row` is unholy, add `dp[i][prev_row][curr_row]` to `dp[i+2][next_prev_row][next_curr_row]`. - Final result: Sum of `dp[8][prev_row][curr_row]` for all possible `prev_row` and `curr_row`. **4. Implementation Details:** - Use nested loops to iterate through all possible row combinations. - Use bitwise operations for efficiency in `is_unholy`. - Use a 3D array for dynamic programming. ## C Implementation
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> // Checks if a pair of rows is unholy int is_unholy(uint64_t prev_row, uint64_t curr_row) { for (int j = 0; j < 8; j++) { if ((curr_row >> j) & 1) { // If cell is 1 int isolated = 1; if (j > 0 && ((curr_row >> (j - 1)) & 1)) isolated = 0; // Left if (j < 7 && ((curr_row >> (j + 1)) & 1)) isolated = 0; // Right if ((prev_row >> j) & 1) isolated = 0; // Up if (((uint64_t)1 << j) & (1ULL << 63)) continue; if (((curr_row << 1) >> j) & 1) isolated = 0; if (isolated) return 0; // Found an isolated 1 } } return 1; } int main() { long long dp[9][256][256] = {0}; // Base case: 2x8 matrices for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { dp[2][prev][curr] = is_unholy(prev, curr); } } // Dynamic programming for (int i = 2; i <= 6; i += 2) { for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { for (uint64_t next_prev = 0; next_prev < 256; next_prev++) { for(uint64_t next_curr = 0; next_curr < 256; next_curr++) { if(is_unholy(curr, next_prev) && is_unholy(next_prev, next_curr)) dp[i+2][next_prev][next_curr] += dp[i][prev][curr]; } } } } } // Calculate total count long long total_count = 0; for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { total_count += dp[8][prev][curr]; } } printf("Total unholy 8x8 matrices: %lld\n", total_count); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> // Checks if a pair of rows is unholy int is_unholy(uint64_t prev_row, uint64_t curr_row) { for (int j = 0; j < 8; j++) { if ((curr_row >> j) & 1) { // If cell is 1 int isolated = 1; if (j > 0 && ((curr_row >> (j - 1)) & 1)) isolated = 0; // Left if (j < 7 && ((curr_row >> (j + 1)) & 1)) isolated = 0; // Right if ((prev_row >> j) & 1) isolated = 0; // Up if (((uint64_t)1 << j) & (1ULL << 63)) continue; if (((curr_row << 1) >> j) & 1) isolated = 0; if (isolated) return 0; // Found an isolated 1 } } return 1; } int main() { long long dp[9][256][256] = {0}; // Base case: 2x8 matrices for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { dp[2][prev][curr] = is_unholy(prev, curr); } } // Dynamic programming for (int i = 2; i <= 6; i += 2) { for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { for (uint64_t next_prev = 0; next_prev < 256; next_prev++) { for(uint64_t next_curr = 0; next_curr < 256; next_curr++) { if(is_unholy(curr, next_prev) && is_unholy(next_prev, next_curr)) dp[i+2][next_prev][next_curr] += dp[i][prev][curr]; } } } } } // Calculate total count long long total_count = 0; for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { total_count += dp[8][prev][curr]; } } printf("Total unholy 8x8 matrices: %lld\n", total_count); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> // Checks if a pair of rows is unholy int is_unholy(uint64_t prev_row, uint64_t curr_row) { for (int j = 0; j < 8; j++) { if ((curr_row >> j) & 1) { // If cell is 1 int isolated = 1; if (j > 0 && ((curr_row >> (j - 1)) & 1)) isolated = 0; // Left if (j < 7 && ((curr_row >> (j + 1)) & 1)) isolated = 0; // Right if ((prev_row >> j) & 1) isolated = 0; // Up if (((uint64_t)1 << j) & (1ULL << 63)) continue; if (((curr_row << 1) >> j) & 1) isolated = 0; if (isolated) return 0; // Found an isolated 1 } } return 1; } int main() { long long dp[9][256][256] = {0}; // Base case: 2x8 matrices for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { dp[2][prev][curr] = is_unholy(prev, curr); } } // Dynamic programming for (int i = 2; i <= 6; i += 2) { for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { for (uint64_t next_prev = 0; next_prev < 256; next_prev++) { for(uint64_t next_curr = 0; next_curr < 256; next_curr++) { if(is_unholy(curr, next_prev) && is_unholy(next_prev, next_curr)) dp[i+2][next_prev][next_curr] += dp[i][prev][curr]; } } } } } // Calculate total count long long total_count = 0; for (uint64_t prev = 0; prev < 256; prev++) { for (uint64_t curr = 0; curr < 256; curr++) { total_count += dp[8][prev][curr]; } } printf("Total unholy 8x8 matrices: %lld\n", total_count); return 0; } |
Timeout: function took too long to complete
Testing if the previous output contains the string 1121231537486377866
: False
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
## Plan for Counting Unholy 8x8 Matrices 1. **Representing the Matrix:** Use an `unsigned long` (64 bits) to represent each row of the 8x8 matrix. Eight `unsigned long` variables will represent the entire matrix. This allows for efficient bitwise operations. 2. **`is_unholy()` function:** This function will take two rows (represented as `unsigned long`) as input and check if there are any isolated 1s in the first row, considering its neighbors in the same row and the provided second row. 3. **Dynamic Programming:** - Create a table `dp[rows][prev_row][curr_row]` where: - `rows` is the number of rows already processed (0 to 8). - `prev_row` and `curr_row` are the bit representations of the last two rows. - `dp[rows][prev_row][curr_row]` stores the number of unholy matrices ending with `prev_row` and `curr_row` having processed `rows` rows. 4. **Base Case:** `dp[2][prev_row][curr_row]` will be 1 if the combination of the first two rows (`prev_row` and `curr_row`) is unholy, and 0 otherwise. 5. **Recursive Step:** Iterate through all possible next two rows (`next_prev_row` and `next_curr_row`). If the combination of `curr_row` and `next_curr_row` is unholy, update the `dp` table: `dp[rows+2][next_prev_row][next_curr_row] += dp[rows][prev_row][curr_row]` 6. **Final Result:** The sum of all `dp[8][prev_row][curr_row]` for all possible `prev_row` and `curr_row` will be the total count of unholy 8x8 matrices. ## C Implementation
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> // Check if the first row is unholy, considering the second row int is_unholy(uint64_t row1, uint64_t row2) { for (int i = 0; i < 8; i++) { if ((row1 >> i) & 1) { // If there's a 1 at position i int isolated = 1; if (i > 0 && ((row1 >> (i - 1)) & 1)) isolated = 0; // Check left if (i < 7 && ((row1 >> (i + 1)) & 1)) isolated = 0; // Check right if ((row2 >> i) & 1) isolated = 0; // Check below if (i>0 && ((row2 >> (i-1)) & 1)) isolated = 0; if (i<7 && ((row2 >> (i+1)) & 1)) isolated = 0; if (isolated) return 0; // Found an isolated 1 } } return 1; } int main() { long long dp[9][256][256] = {0}; for (uint64_t row1 = 0; row1 < 256; row1++) { for (uint64_t row2 = 0; row2 < 256; row2++) { if (is_unholy(row1, row2) && is_unholy(row2,0)) { //Consider edge case for first two rows dp[2][row1][row2] = 1; } } } for (int rows = 2; rows < 8; rows += 2) { for (uint64_t prev_row = 0; prev_row < 256; prev_row++) { for (uint64_t curr_row = 0; curr_row < 256; curr_row++) { for (uint64_t next_prev_row = 0; next_prev_row < 256; next_prev_row++) { for (uint64_t next_curr_row = 0; next_curr_row < 256; next_curr_row++) { if (is_unholy(curr_row, next_curr_row)) { dp[rows + 2][next_prev_row][next_curr_row] += dp[rows][prev_row][curr_row]; } } } } } } long long total_unholy = 0; for (uint64_t prev_row = 0; prev_row < 256; prev_row++) { for (uint64_t curr_row = 0; curr_row < 256; curr_row++) { total_unholy += dp[8][prev_row][curr_row]; } } printf("Total number of unholy 8x8 matrices: %lld\n", total_unholy); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> // Check if the first row is unholy, considering the second row int is_unholy(uint64_t row1, uint64_t row2) { for (int i = 0; i < 8; i++) { if ((row1 >> i) & 1) { // If there's a 1 at position i int isolated = 1; if (i > 0 && ((row1 >> (i - 1)) & 1)) isolated = 0; // Check left if (i < 7 && ((row1 >> (i + 1)) & 1)) isolated = 0; // Check right if ((row2 >> i) & 1) isolated = 0; // Check below if (i>0 && ((row2 >> (i-1)) & 1)) isolated = 0; if (i<7 && ((row2 >> (i+1)) & 1)) isolated = 0; if (isolated) return 0; // Found an isolated 1 } } return 1; } int main() { long long dp[9][256][256] = {0}; for (uint64_t row1 = 0; row1 < 256; row1++) { for (uint64_t row2 = 0; row2 < 256; row2++) { if (is_unholy(row1, row2) && is_unholy(row2,0)) { //Consider edge case for first two rows dp[2][row1][row2] = 1; } } } for (int rows = 2; rows < 8; rows += 2) { for (uint64_t prev_row = 0; prev_row < 256; prev_row++) { for (uint64_t curr_row = 0; curr_row < 256; curr_row++) { for (uint64_t next_prev_row = 0; next_prev_row < 256; next_prev_row++) { for (uint64_t next_curr_row = 0; next_curr_row < 256; next_curr_row++) { if (is_unholy(curr_row, next_curr_row)) { dp[rows + 2][next_prev_row][next_curr_row] += dp[rows][prev_row][curr_row]; } } } } } } long long total_unholy = 0; for (uint64_t prev_row = 0; prev_row < 256; prev_row++) { for (uint64_t curr_row = 0; curr_row < 256; curr_row++) { total_unholy += dp[8][prev_row][curr_row]; } } printf("Total number of unholy 8x8 matrices: %lld\n", total_unholy); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> // Check if the first row is unholy, considering the second row int is_unholy(uint64_t row1, uint64_t row2) { for (int i = 0; i < 8; i++) { if ((row1 >> i) & 1) { // If there's a 1 at position i int isolated = 1; if (i > 0 && ((row1 >> (i - 1)) & 1)) isolated = 0; // Check left if (i < 7 && ((row1 >> (i + 1)) & 1)) isolated = 0; // Check right if ((row2 >> i) & 1) isolated = 0; // Check below if (i>0 && ((row2 >> (i-1)) & 1)) isolated = 0; if (i<7 && ((row2 >> (i+1)) & 1)) isolated = 0; if (isolated) return 0; // Found an isolated 1 } } return 1; } int main() { long long dp[9][256][256] = {0}; for (uint64_t row1 = 0; row1 < 256; row1++) { for (uint64_t row2 = 0; row2 < 256; row2++) { if (is_unholy(row1, row2) && is_unholy(row2,0)) { //Consider edge case for first two rows dp[2][row1][row2] = 1; } } } for (int rows = 2; rows < 8; rows += 2) { for (uint64_t prev_row = 0; prev_row < 256; prev_row++) { for (uint64_t curr_row = 0; curr_row < 256; curr_row++) { for (uint64_t next_prev_row = 0; next_prev_row < 256; next_prev_row++) { for (uint64_t next_curr_row = 0; next_curr_row < 256; next_curr_row++) { if (is_unholy(curr_row, next_curr_row)) { dp[rows + 2][next_prev_row][next_curr_row] += dp[rows][prev_row][curr_row]; } } } } } } long long total_unholy = 0; for (uint64_t prev_row = 0; prev_row < 256; prev_row++) { for (uint64_t curr_row = 0; curr_row < 256; curr_row++) { total_unholy += dp[8][prev_row][curr_row]; } } printf("Total number of unholy 8x8 matrices: %lld\n", total_unholy); return 0; } |
Timeout: function took too long to complete
Testing if the previous output contains the string 1121231537486377866
: False
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
## Plan for Counting Unholy 8x8 Matrices 1. **Representing the matrix:** Use `unsigned long long` (64 bits) to represent each row of the 8x8 matrix. An 8x8 matrix will be an array of 8 `unsigned long long`s. 2. **`is_unholy()` function:** This function will take two rows (current and previous) as input and check if any 1 in the current row is isolated. It will use bitwise operations to check for neighboring 1s (left, right, up, down). 3. **Dynamic Programming:** - Create a DP table `dp[rows][prev_row1][prev_row2]` where: - `rows` is the number of rows processed so far (0 to 8). - `prev_row1` and `prev_row2` are the bit representations of the two previous rows. - Base case: `dp[0][0][0] = 1` (empty matrix is unholy). - Recursively calculate `dp[rows][prev_row1][prev_row2]` by iterating through all possible next two rows (`next_row1`, `next_row2`). If the combination of `prev_row1`, `prev_row2`, `next_row1`, and `next_row2` forms an unholy submatrix, add `dp[rows-2][prev_prev_row1][prev_prev_row2]` to the current DP entry. We can save the two previous rows in variables to avoid another dimension in the DP table. - Final result: `dp[8][0][0]` (assuming we pad the matrix with two rows of zeros at the beginning). ## C Implementation
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | #include <stdio.h> #include <stdint.h> typedef unsigned long long ull; // Checks if a 1 at position 'bit' in 'row' is isolated, given the previous row 'prev_row' int is_isolated(ull row, ull prev_row, int bit) { if (!(row & (1ULL << bit))) return 0; // Not a 1 // Check neighbors if ((row & (1ULL << (bit - 1))) || (row & (1ULL << (bit + 1))) || (prev_row & (1ULL << bit))) return 0; // Not isolated return 1; // Isolated } // Checks if two new rows added to the matrix maintain the unholy property int is_unholy(ull prev_row1, ull prev_row2, ull next_row1, ull next_row2) { for (int i = 0; i < 8; ++i) { if (is_isolated(next_row1, prev_row1, i) || is_isolated(next_row2, next_row1, i)) { return 0; } } return 1; } int main() { long long dp[9][256][256] = {0}; dp[0][0][0] = 1; for(int i = 2; i <= 8; i+=2) { for(int prev1 = 0; prev1 < 256; prev1++) { for (int prev2 = 0; prev2 < 256; prev2++) { for(int next1 = 0; next1 < 256; next1++) { for(int next2 = 0; next2 < 256; next2++) { if(is_unholy(prev1, prev2, next1, next2)) { dp[i][next1][next2] += dp[i-2][prev1][prev2]; } } } } } } printf("Number of unholy 8x8 matrices: %lld\n", dp[8][0][0]); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | #include <stdio.h> #include <stdint.h> typedef unsigned long long ull; // Checks if a 1 at position 'bit' in 'row' is isolated, given the previous row 'prev_row' int is_isolated(ull row, ull prev_row, int bit) { if (!(row & (1ULL << bit))) return 0; // Not a 1 // Check neighbors if ((row & (1ULL << (bit - 1))) || (row & (1ULL << (bit + 1))) || (prev_row & (1ULL << bit))) return 0; // Not isolated return 1; // Isolated } // Checks if two new rows added to the matrix maintain the unholy property int is_unholy(ull prev_row1, ull prev_row2, ull next_row1, ull next_row2) { for (int i = 0; i < 8; ++i) { if (is_isolated(next_row1, prev_row1, i) || is_isolated(next_row2, next_row1, i)) { return 0; } } return 1; } int main() { long long dp[9][256][256] = {0}; dp[0][0][0] = 1; for(int i = 2; i <= 8; i+=2) { for(int prev1 = 0; prev1 < 256; prev1++) { for (int prev2 = 0; prev2 < 256; prev2++) { for(int next1 = 0; next1 < 256; next1++) { for(int next2 = 0; next2 < 256; next2++) { if(is_unholy(prev1, prev2, next1, next2)) { dp[i][next1][next2] += dp[i-2][prev1][prev2]; } } } } } } printf("Number of unholy 8x8 matrices: %lld\n", dp[8][0][0]); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | #include <stdio.h> #include <stdint.h> typedef unsigned long long ull; // Checks if a 1 at position 'bit' in 'row' is isolated, given the previous row 'prev_row' int is_isolated(ull row, ull prev_row, int bit) { if (!(row & (1ULL << bit))) return 0; // Not a 1 // Check neighbors if ((row & (1ULL << (bit - 1))) || (row & (1ULL << (bit + 1))) || (prev_row & (1ULL << bit))) return 0; // Not isolated return 1; // Isolated } // Checks if two new rows added to the matrix maintain the unholy property int is_unholy(ull prev_row1, ull prev_row2, ull next_row1, ull next_row2) { for (int i = 0; i < 8; ++i) { if (is_isolated(next_row1, prev_row1, i) || is_isolated(next_row2, next_row1, i)) { return 0; } } return 1; } int main() { long long dp[9][256][256] = {0}; dp[0][0][0] = 1; for(int i = 2; i <= 8; i+=2) { for(int prev1 = 0; prev1 < 256; prev1++) { for (int prev2 = 0; prev2 < 256; prev2++) { for(int next1 = 0; next1 < 256; next1++) { for(int next2 = 0; next2 < 256; next2++) { if(is_unholy(prev1, prev2, next1, next2)) { dp[i][next1][next2] += dp[i-2][prev1][prev2]; } } } } } } printf("Number of unholy 8x8 matrices: %lld\n", dp[8][0][0]); return 0; } |
Timeout: function took too long to complete
Testing if the previous output contains the string 1121231537486377866
: False
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
A binary 8x8 matrix is 'unholy' if there are no isolated 1s. A 1 is isolated if there isn't another 1 in any of the 4 direct cardinal directions. Write a C program that counts the total number of unholy 8x8 matricies.To solve this question: - Use bit arithmetic and an unsigned long to represent the matrix. - Write a function is_unholy that tests if a matrix is unholy by bit-shifting and masking. Use a dynamic program to count the number of unholy matricies. - Recurse on the number of rows the matrix has. - Enumerate all 2^16 next two rows. This is enough to completely isolate the prior solutions from the next. Write out a plan for the program, and then implement the plan in C.
## Plan for Counting Unholy 8x8 Matrices 1. **Representing the matrix:** Each row of the 8x8 matrix will be represented by an unsigned long (64 bits, enough for 8 columns). The entire matrix can be represented as an array of 8 unsigned longs. 2. **`is_unholy()` function:** This function takes an array of unsigned longs representing the matrix and returns 1 if the matrix is unholy, 0 otherwise. It checks each 1 in the matrix and ensures it has a neighboring 1 in at least one of the four cardinal directions. 3. **Dynamic Programming:** - We'll use a recursive function `count_unholy(row, prev_row, prev_prev_row)` where `row` is the current row being constructed. - `prev_row` and `prev_prev_row` store the bit patterns of the two preceding rows. We need two previous rows to check for isolation. - The base case is when `row == 8`, meaning we have a complete 8x8 matrix. In this case, we call `is_unholy()` and return 1 if it's unholy, 0 otherwise. - For the recursive step, we iterate through all 2^8 possible bit patterns for the current row. For each pattern, we check if placing it creates an unholy submatrix (considering the previous two rows). If so, we recursively call `count_unholy(row + 1, current_row, prev_row)`. - The final result is the sum of all recursive calls. 4. **Optimization:** Memoization can be used to store the results of `count_unholy()` for previously computed states (combinations of `row`, `prev_row`, `prev_prev_row`), avoiding redundant calculations. A 3D array can be used for this. However, given the size of the problem, memoization might not provide a significant speedup, and might consume excessive memory. ## C Implementation
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 | #include <stdio.h> #include <stdint.h> // Check if a matrix is unholy int is_unholy(uint64_t matrix[8]) { for (int i = 0; i < 8; i++) { for (int j = 0; j < 8; j++) { if ((matrix[i] >> j) & 1) { // Check if the bit is 1 int isolated = 1; if (i > 0 && ((matrix[i - 1] >> j) & 1)) isolated = 0; // Check up if (i < 7 && ((matrix[i + 1] >> j) & 1)) isolated = 0; // Check down if (j > 0 && ((matrix[i] >> (j - 1)) & 1)) isolated = 0; // Check left if (j < 7 && ((matrix[i] >> (j + 1)) & 1)) isolated = 0; // Check right if (isolated) return 0; // Found an isolated 1 } } } return 1; // No isolated 1s found } uint64_t count_unholy(int row, uint64_t prev_row, uint64_t prev_prev_row) { if (row == 8) { uint64_t matrix[8] = {0}; // Initialize a temporary matrix matrix[6] = prev_prev_row; matrix[7] = prev_row; return is_unholy(matrix); } uint64_t count = 0; for (uint64_t current_row = 0; current_row < 256; current_row++) { uint64_t matrix[8] = {0}; if (row > 0) matrix[row-1] = prev_prev_row; if (row > 1) matrix[row] = prev_row; matrix[row + 1] = current_row; // For checking isolation int unholy_so_far = 1; if(row > 0 && row < 7) unholy_so_far = is_unholy(matrix); if(unholy_so_far) count += count_unholy(row + 1, current_row, prev_row); } return count; } int main() { uint64_t total_unholy = 0; for (uint64_t first_row = 0; first_row < 256; first_row++){ for(uint64_t second_row = 0; second_row < 256; second_row++){ total_unholy += count_unholy(2, second_row, first_row); } } printf("Total number of unholy 8x8 matrices: %lu\n", total_unholy); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 | #include <stdio.h> #include <stdint.h> // Check if a matrix is unholy int is_unholy(uint64_t matrix[8]) { for (int i = 0; i < 8; i++) { for (int j = 0; j < 8; j++) { if ((matrix[i] >> j) & 1) { // Check if the bit is 1 int isolated = 1; if (i > 0 && ((matrix[i - 1] >> j) & 1)) isolated = 0; // Check up if (i < 7 && ((matrix[i + 1] >> j) & 1)) isolated = 0; // Check down if (j > 0 && ((matrix[i] >> (j - 1)) & 1)) isolated = 0; // Check left if (j < 7 && ((matrix[i] >> (j + 1)) & 1)) isolated = 0; // Check right if (isolated) return 0; // Found an isolated 1 } } } return 1; // No isolated 1s found } uint64_t count_unholy(int row, uint64_t prev_row, uint64_t prev_prev_row) { if (row == 8) { uint64_t matrix[8] = {0}; // Initialize a temporary matrix matrix[6] = prev_prev_row; matrix[7] = prev_row; return is_unholy(matrix); } uint64_t count = 0; for (uint64_t current_row = 0; current_row < 256; current_row++) { uint64_t matrix[8] = {0}; if (row > 0) matrix[row-1] = prev_prev_row; if (row > 1) matrix[row] = prev_row; matrix[row + 1] = current_row; // For checking isolation int unholy_so_far = 1; if(row > 0 && row < 7) unholy_so_far = is_unholy(matrix); if(unholy_so_far) count += count_unholy(row + 1, current_row, prev_row); } return count; } int main() { uint64_t total_unholy = 0; for (uint64_t first_row = 0; first_row < 256; first_row++){ for(uint64_t second_row = 0; second_row < 256; second_row++){ total_unholy += count_unholy(2, second_row, first_row); } } printf("Total number of unholy 8x8 matrices: %lu\n", total_unholy); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 | #include <stdio.h> #include <stdint.h> // Check if a matrix is unholy int is_unholy(uint64_t matrix[8]) { for (int i = 0; i < 8; i++) { for (int j = 0; j < 8; j++) { if ((matrix[i] >> j) & 1) { // Check if the bit is 1 int isolated = 1; if (i > 0 && ((matrix[i - 1] >> j) & 1)) isolated = 0; // Check up if (i < 7 && ((matrix[i + 1] >> j) & 1)) isolated = 0; // Check down if (j > 0 && ((matrix[i] >> (j - 1)) & 1)) isolated = 0; // Check left if (j < 7 && ((matrix[i] >> (j + 1)) & 1)) isolated = 0; // Check right if (isolated) return 0; // Found an isolated 1 } } } return 1; // No isolated 1s found } uint64_t count_unholy(int row, uint64_t prev_row, uint64_t prev_prev_row) { if (row == 8) { uint64_t matrix[8] = {0}; // Initialize a temporary matrix matrix[6] = prev_prev_row; matrix[7] = prev_row; return is_unholy(matrix); } uint64_t count = 0; for (uint64_t current_row = 0; current_row < 256; current_row++) { uint64_t matrix[8] = {0}; if (row > 0) matrix[row-1] = prev_prev_row; if (row > 1) matrix[row] = prev_row; matrix[row + 1] = current_row; // For checking isolation int unholy_so_far = 1; if(row > 0 && row < 7) unholy_so_far = is_unholy(matrix); if(unholy_so_far) count += count_unholy(row + 1, current_row, prev_row); } return count; } int main() { uint64_t total_unholy = 0; for (uint64_t first_row = 0; first_row < 256; first_row++){ for(uint64_t second_row = 0; second_row < 256; second_row++){ total_unholy += count_unholy(2, second_row, first_row); } } printf("Total number of unholy 8x8 matrices: %lu\n", total_unholy); return 0; } |
Timeout: function took too long to complete
Testing if the previous output contains the string 1121231537486377866
: False