Tietoverkko

#include<bits/stdc++.h>
using namespace std;

vector<int> v[101010];

bool z[101010];
int p[101010];

int nn;

void haku(int n, int am, int pp) {
  if(z[n]) {
    cout << nn-(am-p[n]);
    exit(0);
  }
  z[n] = true;
  p[n] = am;
  for(int u : v[n]) {
    if(u != pp) haku(u,am+1,n);
  }
}

int main() {
  for(int i=0; i < 101010; i++) z[i] = false;
  cin >> nn;
  for(int i = 0; i < nn; i++) {
    int a, b; cin >> a >> b;
    v[a].push_back(b);
    v[b].push_back(a);
  }
  haku(1,0,1);
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED