Submission #896529

#	Time	Username	Problem	Language	Result	Execution time	Memory
896529		borisAngelov	Star triangles (IZhO11_triangle)	C++17	100 / 100	80 ms	11860 KiB

triangle

#include <bits/stdc++.h>

using namespace std;

const int maxn = 300005;

int n;

pair<int, int> a[maxn];

unordered_map<int, int> byX;
unordered_map<int, int> byY;

void fastIO()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int main()
{
    fastIO();

    cin >> n;

    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i].first >> a[i].second;
        ++byX[a[i].first];
        ++byY[a[i].second];
    }

    long long ans = 0;

    for (int i = 1; i <= n; ++i)
    {
        int cnt1 = byX[a[i].first] - 1;
        int cnt2 = byY[a[i].second] - 1;
        ans += (1LL * cnt1) * (1LL * cnt2);
    }

    cout << ans << endl;

    return 0;
}

• Subtask 1: 100 / 100