Submission #887786

#	Time	Username	Problem	Language	Result	Execution time	Memory
887786		stdfloat	Star triangles (IZhO11_triangle)	C++17	100 / 100	382 ms	25440 KiB

triangle

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

using ll = long long;

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);

    int n;
    cin >> n;

    map<int, int> my;
    map<int, set<int>> mx;
    for (int i = 0; i < n; i++) {
        int x, y;
        cin >> x >> y;

        my[y]++;
        mx[x].insert(y);
    }

    int ans = 0;
    for (auto i : mx) {
        vector<int> p;
        for (auto j : i.second) p.push_back((p.empty() ? 0 : p.back()) + my[j] - 1);

        int x = -1;
        for (auto j : i.second) ans += (x == -1 ? 0 : p[x]) + p.back() - p[++x];
    }

    cout << ans;
}

Compilation message (stderr)

triangle.cpp: In function 'int main()':
triangle.cpp:28:76: warning: operation on 'x' may be undefined [-Wsequence-point]
   28 |         for (auto j : i.second) ans += (x == -1 ? 0 : p[x]) + p.back() - p[++x];
      |                                                                            ^~~
triangle.cpp:28:19: warning: unused variable 'j' [-Wunused-variable]
   28 |         for (auto j : i.second) ans += (x == -1 ? 0 : p[x]) + p.back() - p[++x];
      |                   ^

• Subtask 1: 100 / 100