#include <bits/stdc++.h> using namespace std; #ifdef LOCAL #include "debug.h" #else #define debug(...) 42 #endif int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n; cin >> n; vector<array<array<int, 2>, 2>> cnt(n); array<map<int, vector<array<int, 2>>>, 2> mp; for (int i = 0; i < n; ++i) { int x, y; cin >> x >> y; mp[0][x].push_back({y, i}); mp[1][y].push_back({x, i}); } for (auto it : {0, 1}) { for (auto [x, a] : mp[it]) { sort(a.begin(), a.end()); for (int i = 0; i < a.size(); ) { int j = i; while (j < a.size() && a[j][0] == a[i][0]) { ++j; } array<int, 2> v = {i, int(a.size()) - j}; while (i < j) { cnt[a[i++][1]][it] = v; } } } } long long res = 0; for (int i = 0; i < n; ++i) { for (int x = 0; x < 2; ++x) { for (int y = 0; y < 2; ++y) { res += (long long) cnt[i][0][x] * cnt[i][1][y]; } } } cout << res; return 0; }

triangle.cpp: In function 'int main()':
triangle.cpp:25:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |       for (int i = 0; i < a.size(); ) {
      |                       ~~^~~~~~~~~~
triangle.cpp:27:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |         while (j < a.size() && a[j][0] == a[i][0]) {
      |                ~~^~~~~~~~~~