[BOJ] 1051 : 숫자 정사각형

단순한 완전탐색 문제이다.

#include <bits/stdc++.h>
using namespace std;
 
int n, m, maxv=0;
int arr[50][50];
 
void dfs(int x, int y, int depth) {
    int nx = x + depth;
    int ny = y + depth;
    if (nx < n && ny < m) {
        if (arr[x][y] == arr[nx][y] && arr[x][y] == arr[x][ny] && arr[x][y] == arr[nx][ny]) {
            maxv = max(maxv, (depth + 1)*(depth + 1));
        }
        dfs(x, y, depth + 1);
    }
    else return;
}
 
string s;
int main() {
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    cin >> n >> m;
    for (int i = 0; i < n; i++) {
        cin >> s;
        for (int j = 0; j < m; j++)
            arr[i][j] = s[j] - '0';
    }
    
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            dfs(i, j, 0);
 
    cout << maxv;
}