Submission #3012315

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Source Code Expand

#include <iostream>

using namespace std;

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);//高速化、endlは使わない

  int N,buff;
  int num=1;

  cin >> N;
  int a[100001] = {};
  bool flag[100001] = {};

  for(int i=1; i <= N; i++){
    cin >> a[i];
  }

  int next = a[1];

  while(!flag[next]){
    //cout << "next: " << next << "\n";
    flag[next] = true;
    num += 1;
    if(a[next]==2){
      cout << num << "\n";
      return 0;
    }
    next = a[next];
  }

  cout << -1 << "\n";
  return 0;
}

Submission Info

Judge Result