Point in Polygon

#include <bits/stdc++.h>
using namespace std;

#define I_2D(row, col, width) ((row) * (width) + (col))
#define PRINT_ARR(arr, n)                                                      \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << arr[i] << " ";                                                   \
    }                                                                          \
    cout << "\n";                                                              \
  } while (0)
#define PRINT_VEC_ARR(v, n)                                                    \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << i << ": ";                                                       \
      for (auto item : v[i]) {                                                 \
        cout << item << " ";                                                   \
      }                                                                        \
      cout << endl;                                                            \
    }                                                                          \
  } while (0)
#define endl '\n';

typedef long long ll;
typedef complex<ll> P;
#define X real()
#define Y imag()
#define CP(a, b, c) ((conj(c - a) * (c - b)).Y)

bool cmp(const P &a, const P &b) {
  return (a.X == b.X) ? (a.Y < b.Y) : (a.X < b.X);
}

bool is_on_the_line(const P a, const P b, const P p) {
  vector<P> pp{a, b, p};
  sort(pp.begin(), pp.end(), cmp);
  return pp[1] == p;
}

bool in_range(P a, P b, P p) {
  if (a.Y > b.Y) {
    auto tmp = a;
    a = b;
    b = tmp;
  }

  return a.Y < p.Y && p.Y < b.Y;
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  P arr[n];
  ll x, y;
  for (int i = 0; i < n; i++) {
    cin >> x >> y;
    arr[i] = {x, y};
  }

  bool boundary = false;
  for (int i = 0; i < m; i++) {
    cin >> x >> y;
    P point = {x, y};
    boundary = false;
    int edges = 0;
    for (int j = 0; j < n; j++) {
      P a = arr[j], b = arr[(j + 1) % n];
      if (CP(a, b, point) == 0 && is_on_the_line(a, b, point)) {
        boundary = true;
        break;
      }

      // if (in_range(a, b, point) && (a.X < point.X || b.X < point.X)) {
      if (a.X <= point.X && point.X < b.X && CP(a, b, point) < 0) {
        edges++;
      } else if (b.X <= point.X && point.X < a.X && CP(b, a, point) < 0) {
        edges++;
      }
    }

    if (boundary) {
      cout << "BOUNDARY" << endl;
    } else if (edges & 1) {
      cout << "INSIDE" << endl;
    } else {
      cout << "OUTSIDE" << endl;
    }
  }
  return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED