Line Segment Intersection

#include <iostream>
#include <ccomplex>
#include <vector>
 
using namespace std;
 
typedef long long C;
typedef complex<C> P;
#define X real()
#define Y imag()
#define cross(a,b) (conj(a)*b).Y
 
bool intersection(P p1, P p2, P p3, P p4){
    if(p1 == p3 or p1 == p4 or p2 == p3 or p2 == p4)return 1;
 
    C c1 = cross(p3-p1,p3-p2);
    C c2 = cross(p4-p1,p4-p2);
 
    //cout << c1 << " " << c2 << endl;
    if((c1>=0 and c2<=0) or (c1<=0 and c2>=0))return true;
    return false;
}
 
int main(){
    int t;
    cin >> t;
    for(int i=0; i< t; i++){
        vector<P> vec(4);
        
        for(int l=0; l<4; l++){
            C a,b;
            cin >> a >> b;
            vec[l] = {a,b};
        }
 
        if(intersection(vec[0], vec[1], vec[2], vec[3])){
            cout << "YES" << endl;
        }
        else cout << "NO" << endl;
 
 
    }
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: ACCEPTED