Submission #1219521

#	Time	Username	Problem	Language	Result	Execution time	Memory
1219521		takoshanava	Star triangles (IZhO11_triangle)	C++20	100 / 100	204 ms	13040 KiB

triangle

#include <bits/stdc++.h>
#define int long long
#define pb push_back
#define fs first
#define sc second
using namespace std;

signed main() {
	int n;
    cin >> n;
    vector<pair<int, int>> p(n);
    vector<int> xs, ys; 

    for(int i = 0; i < n; i++){
        int a, b;
        cin >> a >> b;
        p[i] = {a, b};
        xs.pb(a);
        ys.pb(b);
    }

    sort(xs.begin(), xs.end());
    xs.erase(unique(xs.begin(), xs.end()), xs.end());
    sort(ys.begin(), ys.end());
    ys.erase(unique(ys.begin(), ys.end()), ys.end());

    unordered_map<int, int> nx, ny;
    for(int i = 0; i < xs.size(); i++) nx[xs[i]] = i;
    for(int i = 0; i < ys.size(); i++) ny[ys[i]] = i;

    vector<int> cx(xs.size() + 1, 0), cy(ys.size() + 1, 0);

    for(auto [x, y]:p){
        int xc = nx[x], yc = ny[y];
        cx[xc]++;
        cy[yc]++;
    }

    int ans = 0;
    for(auto [x, y] : p){
        int xc = nx[x], yc = ny[y];
        ans += (cx[xc] - 1) * (cy[yc] - 1);
    }
    cout << ans << endl;
}

• Subtask 1: 100 / 100