Submission #372344

#	Time	Username	Problem	Language	Result	Execution time	Memory
372344		mariowong	Star triangles (IZhO11_triangle)	C++14	100 / 100	241 ms	10860 KiB

triangle

#include <bits/stdc++.h>
using namespace std;

int n,l;
long long ans;
pair<int,int> a[300005];
map <int,int> ct;
int main(){
	ios::sync_with_stdio(false);
	cin >> n;
	for (int i=1;i<=n;i++){
		cin >> a[i].second >> a[i].first;
		ct[a[i].second]++;
	}
	sort(a+1,a+1+n); l=1;
	for (int i=1;i<=n;i++){
		if (i == n || a[i+1].first != a[i].first){
			for (int j=l;j<=i;j++){
				ans+=(long long)(i-l)*(long long)(ct[a[j].second]-1);	
			}
			l=i+1;
		}
	}
	cout << ans << "\n";
	return 0;
}	

• Subtask 1: 100 / 100