This article is made by Jason-Cow.

Welcome to reprint.

But please post the article's address.

 

关键一句话

 

Cross(A[m-1]-R[i],A[m]-R[i])<=0)m--

 

 

 

附加，极角排序，课上讲~~

1 D O; 2 bl acomp(D A,D B){ 3     db x=Cross(A-O,B-O); 4     if(x>0)return 1;if(x<0)return 0; 5     return Dis(O,A)
     
      1 && Cross(A[m-1]-R[i],A[m]-R[i])<=0)m--;15         A[++m]=R[i];16     }17     return m;18 }
     

学了Andrew后，觉得Graham好丑，而且常数还大

唯一的好处是好写，其实差不多