ЗОШ проверка пересечения OK

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#include <math.h>
#define pii pair <int,int>
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}

struct ipn{
    int x,y;
};

struct rpn{
    db x,y;
};

rpn rVec(rpn A, rpn B){
    rpn ab;
    ab.x = A.x - B.x;
    ab.y = A.y - B.y;
    return ab;
}

rpn div(rpn A, rpn B, db p, db q){
    rpn res;
    res.x = (q * A.x + p * B.x) / (p + q);
    res.y = (q * A.y + p * B.y) / (p+q);
    return res;
}

db dot(rpn a, rpn b){
    return a.x * b.x + a.y * b.y;
}

db lgth(rpn a){
    return sqrt(a.x * a.x + a.y * a.y);
}

db angl(rpn a, rpn b){
    db an = acos(dot(a, b) / ( lgth(a) * lgth(b)) );
    return an;
}

db rCross(rpn a, rpn b){
    return a.y * b.x - a.x * b.y;
}

int anglTp(rpn A, rpn B, rpn C){ //возвращает тип угла между AB и AC то есть угла BAC
    rpn ab = rVec(A, B);
    rpn ac = rVec(A, C);
    if (dot(ab, ac) > 0){
        return 1; //острый
    }
    if (dot(ab, ac)  == 0){
        return 1;//прямой
    }
    return 2; // тупой
}



db rArea(rpn A, rpn B, rpn C){
    rpn ab = rVec(A, B);
    rpn ac = rVec(A, C);
    return fabs( rCross(ab, ac)  ); // 2.0
}


db hgt(rpn A, rpn B, rpn C){ //height
    db  h;
    //cout<<"rArea(B, A, C)  = "<<rArea(B, A, C) <<"\n";
    //cout<<"AB = "<<lgth(rVec(A, B))<<"\n";
    h =  rArea(B, A, C) / lgth( rVec(A, B) );
    //cout<<"h = "<<h<<"\n";
    if ( anglTp(A, B, C) == 2){
        //cout<<"one\n";
        return lgth( rVec(C, A) );
    }
    if (anglTp (B, A, C) == 2){
        //cout<<"two\n";
        return lgth( rVec(C, B) );
    }
    return h;
}

void mk(rpn &x){
    cin>>x.x>>x.y;
}

db eps = 1e-7;

int sgn(db x){
    if (x > 0.0) return 1;
    else if (x == 0.0) return 0;
    return -1;
}

bool eq(rpn A, rpn B){
    return A.x == B.x && A.y == B.y;
}

bool inter(rpn A, rpn B, rpn C, rpn D){
    if (eq(A,C) || eq(A,D ) || eq(B, C) || eq(B,D)){
        return 1;
    }
    if (A.x > B.x) swap(A, B);
    if (C.x > D.x) swap(C, D);
    if (B.x < C.x) {
            //cout<<"one\n";
            return 0;
    }
    if (D.x < A.x) {
        //cout<<"two\n";
            return 0;
    }
    if (A.y > B.y) swap(A, B);
    if (C.y > D.y) swap(C, D);
    if (B.y < C.y) return 0;
    if (D.y < A.y ) return 0;

    if ( sgn(rCross(rVec(A,B), rVec(C,D)) == 0.0) ){
        return 1;
    }
    if (sgn(rCross(rVec(A,B), rVec(A,C))) == sgn(rCross(rVec(A,B), rVec(A,D)))){
        /*cout<<"three\n";
        //сout<<"sgn(rCross(rVec(A,B), rVec(A,C))) = "<<sgn(rCross(rVec(A,B), rVec(A,C)))<<"\n";
        cout<<"sgn(rCross(rVec(A,B), rVec(A,C))) = "<<sgn(rCross(rVec(A,B), rVec(A,C)))<<"\n";
        cout<<"sgn(rCross(rVec(A,B), rVec(A,D))) = "<<sgn(rCross(rVec(A,B), rVec(A,D)))<<"\n";*/
        return 0;
    }
    if (sgn(rCross(rVec(C,D), rVec(C, A))) == sgn(rCross(rVec(C, D), rVec(C,B)))){
        /*cout<<"four\n";
        cout<<"sgn(rCross(rVec(C,D), rVec(C, A))) = "<<sgn(rCross(rVec(C,D), rVec(C, A)))<<"\n";
        cout<<"sgn(rCross(rVec(C, D), rVec(C,B))) = "<<sgn(rCross(rVec(C, D), rVec(C,B)))<<"\n";*/

        return 0;
    }
    return 1;
}


int main()
{
    ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cout.precision(20);
	rpn A,B,C,D;
	mk(A);
	mk(B);
	mk(C);
	mk(D);
	if (inter(A,B, C,D)){
        cout<<"YES\n";
	}
	else cout<<"NO\n";
}

/*
0 0 10 10
0 4 10 4

0 0 10 0
9 0 100 0

1 1 1 6
1 4 3 5

1 1 1 6
3 1 3 6

3 3 12 12
6 6 9 9


3 3 5 6
3 5 7 5

1 2 1 2
1 2 1 2

3 3 5 6
5 6 3 3

3 3 5 6
1 2 4 2

5 4 8 4
3 3 5 6

*/