Witch game

#include <functional>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
using namespace std;
#define rep(i,a,b) for(int i = (a); i < int(b); ++i)
#define rrep(i,a,b) for(int i = (b); i --> int(a); )
#define trav(i,v) for(auto&i:v)
#define all(c) (c).begin(), (c).end()
#define sz(c) int((c).size())
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
int main(){
	cin.tie(0);
	cin.sync_with_stdio(0);
	int n;
	cin >> n;
	vi c(n);
	vector<vector<bool>> close(n,vector<bool>(n,0));
	vector<pii> E;
	rep(i,0,n){
		int j;
		cin >> j;
		if(close[i][--j]) continue;
		E.push_back({i,j});
		close[i][j] = close[j][i] = 1;
		if(i < j) ++c[i];
		else ++c[j];

	}
	ll ans = 0;
	rep(i,0,n){
		long long a = n-i-c[i]-1;
		long long k = a*(a-1)/2;
		trav(j,E) if(j.first > i && j.second > i)
			if(!close[i][j.first] && !close[i][j.second])
				--k;
		ans += k;
	}
	cout << ans << endl;
}

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

Test 11

Group: 3

Verdict: RUNTIME ERROR

Test 12

Group: 3

Verdict: RUNTIME ERROR

Test 13

Group: 3

Verdict: RUNTIME ERROR

Test 14

Group: 3

Verdict: RUNTIME ERROR

Test 15

Group: 3

Verdict: RUNTIME ERROR