제출 #164660

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
164660		ahmet	별들과 삼각형 (IZhO11_triangle)	C++14	0 / 100	2 ms	376 KiB

triangle

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,n) for(long long (i)=0;(i)<(n);++(i))
#define ref(i,a,b) for (long long (i)=(a); (i)<=(b); ++(i))
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define mp make_pair
const long long mx=3e5+5;
// FREOPEN UNUTMA
long long n;
pair <long long,long long>  a[mx];
int main(){
	ios_base::sync_with_stdio(false);cin.tie(NULL);
	/*freopen("triangles.in", "r", stdin);
	freopen("triangles.out", "w", stdout); */
   //
	unordered_map <long long,long long> mp;
	unordered_map <long long,long long> mp2;	
	cin >> n;
	rep(i,n){
		cin >> a[i].first;
		cin >> a[i].second;
		mp.insert(pair <long long,long long>(a[i].first,a[i].nd));
		mp2.insert(pair<long long,long long>(a[i].nd,a[i].st));
	}
	long long ans=0;
	for(long long i=0;i<n;++i){
		ans+=(mp.count(a[i].first)-1)*(mp2.count(a[i].nd)-1);
	//	cout << mp.count(a[i].first) <<" "<< mp2.count(a[i].nd)<< endl;
	}
	cout << ans << endl;
}  	

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