Submission #391573

#	Time	Username	Problem	Language	Result	Execution time	Memory
391573		acm	Star triangles (IZhO11_triangle)	C++14	100 / 100	369 ms	12200 KiB

triangle

#include <bits/stdc++.h>
#define speed                   \
  ios_base::sync_with_stdio(0); \
  cin.tie(0);                   \
  cout.tie(0);
#define precision     \
  cout.precision(30); \
  cerr.precision(10);
#define ll long long
#define ld long double
#define pll pair<ll, ll>
#define pii pair<int, int>
#define forn(n) for (int i = 1; i <= n; i++)
#define forlr(l, r) for (int i = l; i != r; (l > r ? i-- : i++))
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define mp(x, y) make_pair(x, y)
#define all(x) x.begin(), x.end()
#define pc(x) __builtin_popcount(x)
#define pcll(x) __builtin_popcountll(x)
#define F first
#define S second
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void ioi(string name) {
  freopen((name + ".in").c_str(), "r", stdin);
  freopen((name + ".out").c_str(), "w", stdout);
}
int n;
ll t;
pair<int, int> a[500005];
map<int, int> m, k;
int main() {
  speed;
  precision;
  // code
  cin >> n;
  for (int i = 1; i <= n; i++) {
    int x, y;
    cin >> x >> y;
    a[i] = mp(x, y);
    m[x]++;
    k[y]++;
  }
  for (int i = 1; i <= n; i++) {
    t += (ll)(m[a[i].F] - 1) * (k[a[i].S] - 1);
  }
  cout << t;
  // endl
#ifndef ONLINE_JUDGE
  cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
  return 0;
}

Compilation message (stderr)

triangle.cpp: In function 'void ioi(std::string)':
triangle.cpp:26:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   26 |   freopen((name + ".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
triangle.cpp:27:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   27 |   freopen((name + ".out").c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100