Point in Polygon

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

typedef long long ll;
typedef vector<ll> vl;
typedef pair<ll,ll> pl;


typedef long long C;
typedef complex<C> P;
#define X real()
#define Y imag()

#define sz(x) (ll)(x).size()

#define F first
#define S second
#define PB push_back
#define MP make_pair

#define REP(i,a,b) for (ll i = a; i < b; i++)



bool onSegment(P s, P e, P p) {
    //cout << ((conj(s - p)*(e - p)).Y == 0 && ((s - p).X*(e - p).X + (s - p).Y*(e - p).Y) <= 0) << endl;
    return (conj(s - p)*(e - p)).Y == 0 && ((s - p).X*(e - p).X + (s - p).Y*(e - p).Y) <= 0;
}

ll inPolygon(vector<P> &p, P a) {
    ll cnt = 0;
    ll n = sz(p);
    REP(i,0,n) {
        P q = p[(i + 1) % n];

        if (onSegment(p[i], q, a)) {
            //cout << "Boundary" << endl;
            return 2;
        } 

        cnt ^= ((a.Y<p[i].Y) - (a.Y<q.Y)) * (conj(p[i]-a)*(q-a)).Y > 0;
    }
    return cnt;
}


int main() {
    ll n, m;
    cin >> n >> m;

    vector<P> v;

    ll x,y;
    REP(i,0,n) {
        cin >> x >> y;
        v.push_back({x,y});
    }
    
    ll out[m];
    REP(i,0,m) {
        cin >> x >> y;
        out[i] = inPolygon(v, P{x, y});
    }

    REP(i,0,m) {
        if(out[i] == 1) cout << "INSIDE" << endl;
        else if(out[i] == 0) cout << "OUTSIDE" << endl;
        else cout << "BOUNDARY" << endl;
        //cout << out[i] << " " << endl;
    }
    


}

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

Test 14

Verdict: ACCEPTED