제출 #88528

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
88528		1Khan	별들과 삼각형 (IZhO11_triangle)	C++14	0 / 100	2 ms	564 KiB

triangle

// In the name of GOD

#include <bits/stdc++.h>

using namespace std;

#define good exit(0);
#define nl endl
#define ios ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define sz(s) (int)s.size()
#define all(s) s.begin(), s.end()
#define pb push_back
#define bb begin()
#define ee end()
#define ff first
#define ss second
#define ll long long
#define db double
#define pii pair<int, int>

const int N = 3e5 + 555;

int n;
map<int, int> m, k;
int a[N], b[N];
int main(){

     ios

     cin >> n;
     for(int i = 1; i <= n; ++i){
          cin >> a[i] >> b[i];
          m[a[i]]++;
          k[b[i]]++;
     }
     int ans = 0;
     for(int i = 1; i <= n; ++i){
          int q = k[a[i]] - 1;
          int w = m[b[i]] - 1;
          ans += (q * w);
     }
     cout << ans;
     return 0;
}

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