Tanssiaiset

input/code.cpp: In function 'int main()':
input/code.cpp:23:21: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(v[a].size() > 0 && v[a][0] == b || (v[a].size() > 1 && v[a][1] == b)) cout << a << " " << b;
                     ^

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
#define N (1<<20)

int t[N];
vector<int> v[N];

int main(){
	int n; 
	cin >> n;
	int m = n/2+1;
	vector<int> q;
	while(m--){
		int a, b; cin >> a >> b;
		if(t[a]) q.push_back(a);
		if(t[b]) q.push_back(b);
		++t[a], ++t[b];
		v[a].push_back(b);
	}
	int a = q[0], b = q[1];
	if(v[a].size() > 0 && v[a][0] == b || (v[a].size() > 1 && v[a][1] == b)) 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