Tanssiaiset

input/code.cpp: In function 'int main()':
input/code.cpp:19:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
   if(aa[i]==2)
     ^

#include <bits/stdc++.h>

using namespace std;

int n, a, b, aa[101010], k[101010];
set<pair<int,int>> s;

int main() {
	cin >> n;
	for(int i=0; i<n/2+1; i++) {
		cin >> a >> b;
		aa[a]++;
		aa[b]++;
		s.insert(make_pair(a, b));
	}
	a=0;
	b=0;
	for(int i=0; i<=n; i++) {
		if(aa[i]==2)
			if(a)
				b =  i;
			else
				a = i;
	}
	if(s.find(make_pair(a,b))!=s.end())
		cout << a << " " << b;
	else
		cout << b << " " << a;

}

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