제출 #671812

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
671812		moday_morning	별들과 삼각형 (IZhO11_triangle)	C++17	100 / 100	286 ms	9748 KiB

triangle

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 300000;

void usaco(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

map <int, int> x, y;
int a[1 + N][2];
 
void solve() {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i][0] >> a[i][1];
    }
    for (int i = 1; i <= n; i++) {
        x[a[i][0]]++;
        y[a[i][1]]++;
    }
    int sum = 0;
    for (int i = 1;i <= n; i++) {
        sum += 1LL * (x[a[i][0]] - 1) * (y[a[i][1]] - 1);
    }
    cout << sum << "\n";
}

signed main() {
    //usaco("triangles");
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t = 1;
//    cin >> t;
    while (t--) {
        solve();
    }
}

컴파일 시 표준 에러 (stderr) 메시지

triangle.cpp: In function 'void usaco(std::string)':
triangle.cpp:7:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    7 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
triangle.cpp:8:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100