[BOJ] 1051 : 숫자 정사각형

#include <stdio.h>

int n, m, k, i, j;
char a[55][55];

int main() {
	scanf("%d %d", &n, &m);

	for (i = 0; i < n; i++)
		scanf("%s", a[i]);

	k = n < m ? n : m;
	while (k--) for (i = 0; i < n - k; i++) for (int j = 0; j < m - k; j++)
		if (a[i][j] == a[i][j+k] && a[i][j] == a[i+k][j] && a[i][j] == a[i+k][j+k])
			return ~printf("%d", (k+1)*(k+1));

	return 0;
}