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July 19, 2025 09:32
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| //gcc -Wall -Wextra -Werror -std=c98 -o meys biggest_square.c | |
| //echo -e "5.ox\n.....\n.....\noooo.\n.....\n....." | ./meys | |
| #include <stdio.h> | |
| #include <stdlib.h> | |
| #include <unistd.h> | |
| #include <fcntl.h> | |
| int min3(int a, int b, int c) { | |
| int r = a; | |
| if (b < r) r = b; | |
| if (c < r) r = c; | |
| return (r); | |
| } | |
| int err(FILE *file, char *line) { | |
| printf("ERROR\n"); | |
| if (file && file != stdin) fclose(file); | |
| if (line) free(line); | |
| return 1; | |
| } | |
| int main(int ac, char **av) { | |
| if (ac > 2) | |
| return err(NULL, NULL); | |
| FILE *file = NULL; | |
| if (ac == 1) | |
| file = stdin; | |
| if (ac == 2) | |
| file = fopen(av[1], "r"); | |
| if (!file) | |
| return err(file, NULL); | |
| char *line = NULL; | |
| size_t len = 0; | |
| ssize_t bytes = getline(&line, &len, file); | |
| if (bytes == -1) | |
| return err(file, line); | |
| int row = 0, i = 0; | |
| while (line[i] >= '0' && line[i] <= '9') | |
| row = row * 10 + (line[i++] - '0'); | |
| if (i == 0 || row <= 0 || bytes < i + 3) | |
| return err(file, line); | |
| char empt = line[i++]; | |
| char obst = line[i++]; | |
| char full = line[i++]; | |
| if (empt < 32 || empt > 126 || | |
| obst < 32 || obst > 126 || | |
| full < 32 || full > 126 || | |
| empt == obst || empt == full || obst == full) | |
| return err(file, line); | |
| free(line); | |
| line = NULL; | |
| char grid[row][1001]; | |
| int dp[row][1001]; | |
| int col = 0, max_size = 0, max_row = 0, max_col = 0; | |
| for (int r = 0; r < row; r++) { | |
| bytes = getline(&line, &len, file); | |
| if (bytes < 0 || line[bytes - 1] != '\n') | |
| return err(file, line); | |
| line[bytes - 1] = '\0'; | |
| bytes--; | |
| if (r == 0) col = bytes; | |
| else if (bytes != col || col <= 0) | |
| return err(file, line); | |
| for (int c = 0; c < col; c++) { | |
| if (line[c] != empt && line[c] != obst) | |
| return err(file, line); | |
| grid[r][c] = line[c]; | |
| } | |
| grid[r][col] = '\0'; | |
| for (int c = 0; c < col; c++) { | |
| if (grid[r][c] == obst) | |
| dp[r][c] = 0; | |
| else if (r == 0 || c == 0) | |
| dp[r][c] = 1; | |
| else | |
| dp[r][c] = 1 + min3(dp[r-1][c], dp[r][c-1], dp[r-1][c-1]); | |
| if (dp[r][c] > max_size) { | |
| max_size = dp[r][c]; | |
| max_row = r; | |
| max_col = c; | |
| } | |
| } | |
| } | |
| free(line); | |
| if (file != stdin) fclose(file); | |
| for (int r = max_row - max_size + 1; r <= max_row; r++) | |
| for (int c = max_col - max_size + 1; c <= max_col; c++) | |
| grid[r][c] = full; | |
| for (int r = 0; r < row; r++) | |
| printf("%s\n", grid[r]); | |
| } |
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