Point in Polygon

input/code.cpp: In function 'int intersect(P, P, P, P)':
input/code.cpp:54:11: warning: variable 'v1' set but not used [-Wunused-but-set-variable]
   54 |         P v1 = b - a;
      |           ^~
input/code.cpp:55:11: warning: variable 'v2' set but not used [-Wunused-but-set-variable]
   55 |         P v2 = d - c;
      |           ^~

#include <bits/stdc++.h>
#include <climits>
#include <cmath>
 
using namespace std;
using ll = long long;
typedef long long C;
typedef complex<C> P;
#define X real()
#define Y imag()
 
// Debug printing
#ifdef DEBUG
#define deb(fmt, args...) printf("DEBUG: %d: " fmt, __LINE__, ##args)
#define debug_print(fmt, args...) printf(fmt, ##args)
#else
#define deb(fmt, args...)
#define debug_print(fmt, args...)
#endif
 
void print_array(vector<int> in, const string title = "Vector")
{
	debug_print("DEBUG: %s [\nDEBUG: ", title.c_str());
	for (unsigned int i = 0; i < in.size(); i++) {
		debug_print("%d ", in[i]);
	}
	debug_print("\nDEBUG: ] END\n");
}
 
void print_matrix(vector<vector<int> > in, const string title = "Matrix")
{
	debug_print("DEBUG: %s [\nDEBUG: ", title.c_str());
	for (unsigned int i = 0; i < in.size(); i++) {
		for (unsigned int j = 0; j < in[i].size(); j++) {
			debug_print("%d ", in[i][j]);
		}
		debug_print("\nDEBUG: ");
	}
	debug_print("DEBUG: ] END\n");
}
 
double angle(int x1, int y1, int x2, int y2) {
	double dot = x1*x2 + y1*y2;
	double cross = x1*y2 - y1*x2;
	return atan2(cross, dot);
}
 
double dist(int x1, int y1, int x2, int y2) {
	return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

int intersect(P a, P b, P c, P d)
{
	P v1 = b - a;
	P v2 = d - c;

	if (a == c || a == d) {
		return 1;
	}

	// ll cross = (conj(v1)*v2).Y;
	ll x1 = a.X, y1 = a.Y, x2 = b.X, y2 = b.Y;
	ll x3 = c.X, y3 = c.Y, x4 = d.X, y4 = d.Y;
	double err = 0.00000000000001;
	// deb("cross: %lld\n", cross);

	// Same slopes, check if they overlap
	// if (cross == 0) {
		// deb("cross = 0\n");
		// double ac = dist(x1, y1, x3, y3);
		// double cb = dist(x3, y3, x2, y2);
		// double ab = dist(x1, y1, x2, y2);
		double ad = dist(x1, y1, x4, y4);
		// double db = dist(x4, y4, x2, y2);
		// if (abs(ac + cb - ab) <= err) {
		// 	return 1;
		// }
		// if (abs(ad + db - ab) <= err) {
		// 	return 1;
		// }
		double ca = dist(x1, y1, x3, y3);
		double cd = dist(x3, y3, x4, y4);
		// double bd = dist(x2, y2, x4, y4);
		// deb("%lld, %lld, %lld\n", ca, ad, cd);
		if (abs(ca + ad - cd) <= err) {
			return 1;
		}
		// if (abs(cb + bd - cd) <= err) {
		// 	return 1;
		// }
	// }
	double t1 = (1.0 * (x1 - x3) * (y3 - y4) - (y1 - y3) * (x3 - x4));
	double t2 = (1.0 * (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4));
	double u1 = -(1.0 * (x1 - x2) * (y1 - y3) - (y1 - y2) * (x1 - x3));
	double u2 = (1.0 * (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4));

	double t = t1 / t2;
	double u = u1 / u2;
	if (u >= -err && u <= 1.0 + err && t >= -err && t <= 1.0 + err) {
		return 2;
	}
	return 0;
}

int main(int argc, char *argv[])
{
	ios::sync_with_stdio(0);
	cin.tie(0);

	// Read the input parameters
	int n, m;
	cin >> n >> m;

	vector<P> polygon(n + 1);
	int x, y;
	for (int i = 0; i < n; i++) {
		cin >> x >> y;
		polygon[i] = {x, y};
	}
	polygon[n] = polygon[0];

	for (int i = 0; i < m; i++) {
		ll x1, y1;
		cin >> x1 >> y1;
		P a = {x1, y1};
		P b = {2000000000, 2000000000};

		int num = 0;
		bool print = true;
		for (int j = 0; j < n; j++) {
			// deb("j: %d\n", j);
			int res = intersect(a, b, polygon[j], polygon[j + 1]);
			if (res == 1) {
				cout << "BOUNDARY\n";
				print = false;
				break;
			}
			if (res == 2) {
				num++;
			}
		}
		// deb("num %d\n", num);
		if (print && num % 2 == 1) {
			cout << "INSIDE\n";
		}
		if (print && num % 2 == 0){
			cout << "OUTSIDE\n";
		}
	}
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED