Point in Polygon

#include <iostream>
#include <vector>
using namespace std;

#define ll long long int

struct Point {
    ll x, y;
};

ll crossProduct(const Point& p1, const Point& p2,
                const Point& p3) {
    return (p2.x - p1.x) * (p3.y - p1.y) - (p2.y - p1.y) * (p3.x - p1.x);
}

bool isPointOnSegment(const Point& p, const Point& p1,
                      const Point& p2) {
    return crossProduct(p1, p2, p) == 0 && p.x >= min(p1.x, p2.x) 
            && p.x <= max(p1.x, p2.x) && p.y >= min(p1.y, p2.y) && p.y <= max(p1.y, p2.y);
}

ll windingNumber(const vector<Point>& polygon,
                  const Point& point) {
    int n = polygon.size();
    ll windingNumber = 0;

    for (int i = 0; i < n; i++) {
        Point p1 = polygon[i];
        Point p2 = polygon[(i + 1) % n];

        if (isPointOnSegment(point, p1, p2)) {
            return -1;
        }

        if (p1.y <= point.y) {
            if (p2.y > point.y && crossProduct(p1, p2, point) > 0) {
                windingNumber++;
            }
        } else {
            if (p2.y <= point.y && crossProduct(p1, p2, point) < 0) {
                windingNumber--;
            }
        }
    }

    return windingNumber;
}

int main() {
    int n, m;
    cin >> n >> m;
    vector<Point> polygon(n);

    for (int i = 0; i < n; i++) {
        cin >> polygon[i].x;
        cin >> polygon[i].y;
    }

    for (int i = 0; i < m; i++) {
        Point point;
        cin >> point.x;
        cin >> point.y;

        if (windingNumber(polygon, point) == -1)
            cout << "BOUNDARY" << endl;

        else if (windingNumber(polygon, point) == 0)
            cout << "OUTSIDE" << endl;

        else
            cout << "INSIDE" << endl;
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: ACCEPTED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED