Submission #1091709

#	Time	Username	Problem	Language	Result	Execution time	Memory
1091709		KluydQ	Star triangles (IZhO11_triangle)	C++17	0 / 100	1 ms	348 KiB

triangle

#include <bits/stdc++.h>

#define FOR( i, x, n, d ) for( int i = x; i <= n; i += d )

using namespace std;
const int N = 3e5;

int a[N], b[N], x[N], y[N];
long long ans = 0;

int main()
{
//	freopen("triangle.in", "r", stdin);
//	freopen("triangle.out", "w", stdout);
	
	int n; cin >> n;
	
	FOR( i, 1, n, 1 )
	{
		cin >> x[i] >> y[i];
		b[y[i]] ++; 
	}
	FOR( i, 1, n, 1 )
	{
		ans += a[x[i]] * 1ll *  b[y[i]];
		a[x[i]] += b[y[i]];
	}
	cout << ans / 2;
}

• Subtask 1: 0 / 100