View Code of Problem 67

#include<iostream>
#include<vector>
#include<string>
#include <algorithm>
#include <math.h>
using namespace std;

int main() {
    double x1,x2,x3,x4,y1,y2,y3,y4;
   while(~scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2)){
       scanf("%lf%lf%lf%lf",&x3,&y3,&x4,&y4);
       if(x1 != x2 && x3 != x4){

               double k1 = (y2 - y1) / (x2 - x1);
               double k2 = (y4 - y3) / (x4 - x3);

               if(k1 != k2){
                   printf("Yes\n");
               }else if(y1-k1*x1 != y3-k2*x3){
                   printf("No\n");
               }
               else {
                   printf("yes\n");
               }

       }else if(x1 == x2 && x3 == x4 && x1 != x3){
           printf("No\n");
       }else{
           printf("Yes\n");
       }
   }
}