cycle.cpp

#include <iostream>
#include <cmath>
#include <cstdio>

using namespace std;

bool f(bool mat[50][50], bool v[50], int k, int n){
    if (v[k])
        return true;
    v[k] = true;
    bool c[50];
    for (int i = 0; i < n; i++){
        if (mat[k][i]){
            for (int j = 0; j < n; j++)
                c[j] = v[j];
            if (f(mat, c, i, n))
                return true;
        }
    }
    return false;
}

int main(){

    int n;
    cin >> n;
    bool mat[50][50], v[50] = {};
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            cin >> mat[i][j];

    for (int i = 0; i < n; i++){
        if (f(mat, v, i, n)){
            cout << 1 << endl;
            goto END;
        }
    }
    cout << 0 << endl;

    END:
    return 0;
}