View Code of Problem 67

#include<stdio.h>

int main()
{
	float x1,x2,x3,x4,y1,y2,y3,y4,k1,k2;
	while(scanf("%f %f %f %f %f %f %f %f",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4) != EOF)
    {
        if((y2-y1)*(x4-x3) == (y4-y3)*(x2-x1))
        {
            if(x1!=x2&&x3!=x4)
            {
                k1 = (float)(y2-y1)/(x2-x1);
                k2 = (float)(y4-y3)/(x4-x3);
                if(y1-k1*x1 == y4-k2*x4)
                {
                    printf("Yes\n");
                }
                else
                    printf("No\n");
            }
            else
            {
                if(x1==x2&&x3==x4&&x1==x3)
                    printf("Yes\n");
                else
                    printf("No\n");
            }
        }
        else
            printf("Yes\n");
    }
}