Tanssiaiset

#include <iostream>
#include <utility>

using namespace std;

#define N 100001
int taken[N];
pair<int, int> stud[N];

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n; cin >> n; cin.ignore();
	int p = (n / 2) + 1;
	pair<int,int> f = make_pair(0,0),f2=make_pair(0,0);
	int idx = 0;
	
	for (int i = 1; i <= p; i++) {
		int a, b; cin >> a >> b; cin.ignore();
		stud[i] = {a, b};
		if (taken[a] > 0) {
			f={a,taken[a]};
			f2={taken[a],a};
			idx=i;
			break;
		} else if (taken[b] > 0) {
			f={b,taken[b]};
			f2={taken[b],b};
			idx=i;
			break;
		}
		taken[a] = b;
		taken[b] = a;
	}
	
	for (int i = idx - 1; i >= 1; i--) {
		pair<int,int> j=stud[i];
		if (j==f || j == f2) {
			cout << j.first << " " << j.second;
			break;
		}
	}
	
	return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: WRONG ANSWER

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: WRONG ANSWER

Test 5

Group: 1

Verdict: WRONG ANSWER

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: WRONG ANSWER

Test 8

Group: 2

Verdict: WRONG ANSWER

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: WRONG ANSWER