View Code of Problem 67

#include <stdio.h>
#include <math.h>
#include <string.h>
int main()
{
	float x1,y1,x2,y2,x3,y3,x4,y4,k1,k2,b1,b2;
	while(scanf("%f %f %f %f %f %f %f %f",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4)!=EOF){
		k1=(y2-y1)/(x2-x1);     //求斜率 
		k2=(y4-y3)/(x4-x3);
		b1=y1-k1*x1;           
		b2=y3-k2*x3;
		if(x1==x2&&x3==x4&&x1!=x3){
			printf("No\n");
		}
		else if(x1!=x2&&x3!=x4){
			if(k1==k2&&b1!=b2){
				printf("No\n");
			}
			else{
				printf("Yes\n");
			}	
		}
		else{
			printf("Yes\n");
		}
		
	}
	return 0;
}