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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. struct Pt {
  5.     long long x, y;
  6. };
  7. long long cross(Pt a, Pt b, Pt c) {
  8.     return (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);
  9. }
  10. bool on_seg(Pt a, Pt b, Pt p) {
  11.     if (cross(a, b, p) != 0) return false;
  12.     return p.x >= min(a.x, b.x) && p.x <= max(a.x, b.x) &&
  13.            p.y >= min(a.y, b.y) && p.y <= max(a.y, b.y);
  14. }
  15.  
  16. void solve() {
  17.     int n, m;
  18.     if (!(cin >> n >> m)) return;
  19.  
  20.     vector<Pt> p(n);
  21.     for (int i = 0; i < n; i++) cin >> p[i].x >> p[i].y;
  22.  
  23.     while (m--) {
  24.         Pt q;
  25.         cin >> q.x >> q.y;
  26.  
  27.         bool bnd = false;
  28.         int cnt = 0;
  29.  
  30.         for (int i = 0; i < n; i++) {
  31.             Pt a = p[i];
  32.             Pt b = p[(i + 1) % n];
  33.  
  34.             if (on_seg(a, b, q)) {
  35.                 bnd = true;
  36.                 break;
  37.             }
  38.             if (a.y > b.y) swap(a, b);
  39.             if (q.y >= a.y && q.y < b.y && cross(q, a, b) > 0) {
  40.                 cnt++;
  41.             }
  42.         }
  43.  
  44.         if (bnd) cout << "BOUNDARY"<<'\n';
  45.         else if (cnt % 2 == 1) cout << "INSIDE"<<'\n';
  46.         else cout << "OUTSIDE"<<'\n';
  47.     }
  48. }
  49.  
  50. int main() {
  51.     ios_base::sync_with_stdio(0); cin.tie(0);
  52.     solve();
  53.     return 0;
  54. }
  55.  
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/mR6SBQ
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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