View Code of Problem 67

#include <stdio.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 ){ //+
			k1 = 1.0*(y2-y1)/(x2-x1);
			k2 = 1.0*(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");
		}
		
	}
	
 
	return 0;
	
}
/*
Main.cc: In function 'int main()':
Main.cc:10:4: error: 'k1' was not declared in this scope
    k1 = 1.0*(y2-y1)/(x2-x1);
    ^~
Main.cc:10:4: note: suggested alternative: 'y1'
    k1 = 1.0*(y2-y1)/(x2-x1);
    ^~
    y1
Main.cc:11:4: error: 'k2' was not declared in this scope
    k2 = 1.0*(y4-y3)/(x4-x3);
    ^~
Main.cc:11:4: note: suggested alternative: 'y2'
    k2 = 1.0*(y4-y3)/(x4-x3);
    ^~
    y2
*/