Submission #166017

#	Time	Username	Problem	Language	Result	Execution time	Memory
166017		Dovran	Star triangles (IZhO11_triangle)	C++11	100 / 100	1097 ms	9204 KiB

triangle

#include <bits/stdc++.h>
#define N 400009
#define ff first
#define ss second
#define pb push_back
#define ll long long
#define pii pair <ll, ll>

using namespace std;

ll n, ans;
map<ll, ll>a, b;
pii p[N];

int main(){
	cin>>n;
	for(int i=1; i<=n; i++)
		cin>>p[i].ff>>p[i].ss, a[p[i].ff]++, b[p[i].ss]++;
	
	for(int i=1; i<=n; i++)
		ans+=max((ll)0, b[p[i].ss]-1)*max((ll)0, a[p[i].ff]-1);
	
	cout<<ans;

}

• Subtask 1: 100 / 100