zhaozengguang的专栏

写python程序，有时候忘记关闭文件，造成资源占用问题，因此，

def levenshtein(lst1,lst2,i,j): if min(i,j) == 0: return max(i,j)+1 return min( levenshtein(lst1,lst2,i-1,j)+1, levenshtein(lst1,lst2,i,j-1)+1, levenshtein(lst1

Y不动点算子可以表达递归，

''' Implementation of the fixed point combinator Y. -----------------------------------------------   The Y combinator is a higher order f