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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. #define clr(a,b) memset(a,b,sizeof(a))
  5. #define all(v) ((v).begin()),((v).end())
  6. #define read(v) freopen(v, "r", stdin)
  7. #define write(v) freopen(v, "wt", stdout)
  8. #define fastIO cout << fixed << setprecision(8), ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr)
  9. double const EPS = 1e-9, PI = acos(-1);
  10. const int N = 2e3 + 9, M = 2e3 + 9, OO = 1e9 + 7, MOD = 1e9 + 7;
  11. const ll inf = 1e18;
  12.  
  13. map<pair<int, int>, int> slope;
  14. map<int, int> Xs, Ys;
  15. ll Comb[N][5];
  16.  
  17. void pascal(){
  18.   for (int i = 0; i <= 2002; ++i) {
  19.     int m = min(6, i);
  20.     for (int j = 0; j <= m; ++j) {
  21.       if(i == 0 || j == 0) {
  22.         Comb[i][j] = 1;
  23.         continue;
  24.       }
  25.       Comb[i][j] = Comb[i-1][j] + Comb[i-1][j-1];
  26.     }
  27.   }
  28. }
  29.  
  30.  
  31. int main() {
  32.   fastIO;
  33. //  read("input.in");
  34. //  write("input.in");
  35.   int n, a, b, gg;
  36.   cin >> n;
  37.   pascal();
  38.   for (int i = 0; i < n; ++i) {
  39.     cin >> a >> b;
  40.     a += 200, b += 200; // fixing zero in GCD
  41.     Xs[a]++;
  42.     Ys[b]++;
  43.     gg = __gcd(a, b);
  44.     a /= gg, b /= gg;
  45.     slope[{a, b}]++;
  46.   }
  47.   ll ans = Comb[n][3];
  48.   for(auto it: slope) {
  49.     if(it.second >= 3) {
  50.       ans -= Comb[it.second][3];
  51.     }
  52.   }
  53.   for(auto it: Xs) {
  54.     if(it.second >= 3) {
  55.       ans -= Comb[it.second][3];
  56.     }
  57.   }
  58.   for(auto it: Ys) {
  59.     if(it.second >= 3) {
  60.       ans -= Comb[it.second][3];
  61.     }
  62.   }
  63.   cout << ans;
  64.   return 0;
  65. }
  66.  
Success #stdin #stdout 0s 4408KB
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https://ideone.com/iiuxuP
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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