가장 큰 정사각형

#include <iostream>
#include <vector>
#include <string>
#define MAXX 1002
 
using namespace std;
int map[MAXX][MAXX], dp[MAXX][MAXX];
int n, m;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
 
    cin >> n >> m;
 
    for (int i = 1; i <= n; i++) {
        string s;
        cin >> s;
 
        for (int j = 0; j < s.size(); j++) {
            map[i][j+1] = s[j] - 48;
            
        }
    }
    
    int maxN = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            if (map[i][j]) {
                //1일 때 
                dp[i][j] = min(dp[i - 1][j - 1], min(dp[i - 1][j], dp[i][j - 1])) + map[i][j];
                maxN = max(maxN, dp[i][j]);
            }
        }
    }
    
    cout << maxN * maxN << '\n';
    
    return 0;
}