King of the Waves

input/code.cpp: In function 'void f2(int)':
input/code.cpp:23:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0; i<rt[c].size(); ++i){
                                ^

#include <iostream>
#include <vector>
using namespace std;
int n;
string ss[1010];
vector<int> rt[1010];

bool u[1010];

void f(int c){
    u[c]=1;
    for (int i=0; i<n; ++i){
        if (ss[c][i]=='1'){
            if (u[i]) continue;
            rt[c].push_back(i);
            f(i);
        }
    }
}


void f2(int c){
    for (int i=0; i<rt[c].size(); ++i){
        f2(rt[c][i]);
    }
    cout << c << " ";
}


int main(){
    cin >> n;
    for (int i=0; i<n; ++i){
        cin >> ss[i];
    }
    u[0]=1;
    f(0);
    bool can=1;
    for (int i=0; i<n; ++i){
        if (!u[i]){
            can=0;
        }
    }
    if (!can){
        cout << "impossible\n";
    }else{
        f2(0);
        cout << "\n";
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED