Road network

#include <iostream>
using namespace std;

#include <vector>

void visit_ConnectedComponent(long int u, vector<bool> visited, vector<vector<long int>> G) {
  visited[u] = true;
  for (long int v : G[u]) {
    if (not visited[v]) {
      visit_ConnectedComponent(v,visited,G);
    }
  }
}

int main() {
  long int n,m;
  cin >> n >> m;

  vector<vector<long int>> G(n);
  for (long int i=0; i<m; ++i) {
    long int x,y;
    cin >> x >> y;
    x--; y--;
    G[x].push_back(y);
    G[y].push_back(x);
  }

  vector<bool> visited(n,0);
  visit_ConnectedComponent(0,visited,G);

  bool connected = true;
  long int u = 1;
  while (connected) {
    connected = visited[u];
    u++;
  }
  if (connected) cout << "YES" << endl;
  else cout << "NO" << endl << 1 << ' ' << u+1 << endl;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: RUNTIME ERROR

Test 7

Verdict: RUNTIME ERROR

Test 8

Verdict: RUNTIME ERROR

Test 9

Verdict: RUNTIME ERROR

Test 10

Verdict: RUNTIME ERROR

Test 11

Verdict: ACCEPTED