View Code of Problem 67

#include <bits/stdc++.h>
#define INF 0x3f3f3f
using namespace std;
double ks(double x1,double y1,double x2,double y2){
	double k;
	if(x2-x1==0&&y2-y1!=0)
		k=INF;
	else if(x2-x1==0&&y2-y1==0)
		k=0;
	else if(x2-x1!=0)
		k=(y2-y1)/(x2-x1);
	return k;
}
int main(){
	double x1,y1,x2,y2,x3,y3,x4,y4;
	while(cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4){
		double k1,k2,k3;
		k1=ks(x1,y1,x2,y2);
		k2=ks(x3,y3,x4,y4);
		if(k1!=k2)cout<<"Yes"<<endl;
		else if(k1==k2){
			if(x3-x1==0&&y3-y1==0)
			cout<<"Yes"<<endl;
			else{
				k3=ks(x1,y1,x3,y3);
				if(k1==k3)
				cout<<"Yes"<<endl;
				else
				cout<<"No"<<endl;
			}
		}
	}
}