View Code of Problem 67

#include <stdio.h>
int main(){
	int X1,X2,Y1,Y2;
	while(scanf("%d %d %d %d",&X1,&Y1,&X2,&Y2)!=EOF){
		int X3,X4,Y3,Y4;
		scanf("%d %d %d %d",&X3,&Y3,&X4,&Y4);
		float k1,k2;
		if(X1-X2==0){      //两条竖线 
			if(X3-X4!=0) printf("Yes\n");
			else if(X1==X3) printf("Yes\n");
			else printf("No\n");
		}
		else{
		
		 k1=(float)(Y1-Y2)/(X1-X2);
		 k2=(float)(Y3-Y4)/(X3-X4);
		 if(k1!=k2) printf("Yes\n");
		 else{
			 if(Y3-Y1==k1*(X3-X1)){
				 printf("Yes\n");
			 }
		 	 else printf("No\n");
		 }
	    }
	
    }
    return 0;
}