Tietoverkko

#include <bits/stdc++.h>
#define ll long long
#define N (1<<17)
 
using namespace std;
 
vector<int> v[N];
int d[N];
int n;
 
void dfs (int i, int x, int p) {
    if (d[i]) {
        cout<<(n - (x - d[i]))<<endl;
        exit(0);
    }
    d[i] = x;
    for (int j : v[i]) if (j != p) dfs(j, x + 1, i);
}
 
int main () {
    cin>>n;
    for (int i = 0; i < n; i++) {
        int a, b;
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    dfs(1, 1, -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