题解 | 最大正方形

#include <stdio.h>
#include <math.h>

int main() {
    int n;
    scanf("%d\n", &n);
    char matrix[n][n];
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            matrix[i][j] = getchar();
        }
        getchar();
    }
    int area, maxArea = 0;
    int coords[4][2];
    for (int x1 = 0; x1 < n; ++x1) {
        for (int y1 = 0; y1 < n; ++y1) {
            if (matrix[x1][y1] != '#') {
                continue;
            }
            for (int x2 = x1 + 1; x2 < n; ++x2) {
                for (int y2 = 0; y2 < n; ++y2) {
                    if (matrix[x2][y2] != '#') {
                        continue;
                    }
                    int dx = x2 - x1, dy = y2 - y1;
                    int x3 = x1 - dy, y3 = y1 + dx;
                    if (x3 < 0 || x3 >= n || y3 < 0 || y3 >= n || matrix[x3][y3] != '#') {
                        continue;
                    }
                    int x4 = x1 + dx - dy, y4 = y1 + dx + dy;
                    if (x4 < 0 || x4 >= n || y4 < 0 || y4 >= n || matrix[x4][y4] != '#') {
                        continue;
                    }
                    area = pow(x2 - x1, 2) + pow(y2 - y1, 2);
                    if (area > maxArea) {
                        coords[0][0] = x1;
                        coords[0][1] = y1;
                        coords[1][0] = x2;
                        coords[1][1] = y2;
                        coords[2][0] = x3;
                        coords[2][1] = y3;
                        coords[3][0] = x4;
                        coords[3][1] = y4;
                        maxArea = area;
                    }
                }
            }
        }
    }
    for (int i = 0; i < 4; ++i) {
        printf("%d %d\n", coords[i][0] + 1, coords[i][1] + 1);
    }
    return 0;
}