#include<stdio.h> int main() { double x1,x2,x3,x4,y1,y2,y3,y4; while(scanf("%lf %lf %lf %lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4)!=EOF) { double k1,k2; if(x1==x2&&x3==x4) { if(x1==x3) printf("YES\n"); else printf("NO\n"); } else { k1=(y1-y2)/(x1-x2); k2=(y3-y4)/(x3-x4); double b1,b2; b1=y1-k1*x1; b2=y3-k2*x3; if(k1==k2&&b1!=b2)//两线段平行 printf("NO\n"); else printf("YES\n"); } } } |
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