python 排序 由大到小

import functools

class Solution:
    # @param {integer[]} nums
    # @return {string}
    def largestNumber(self, nums):

        def comparator(x, y):   # inputs are string representations of non-negative ints
            if x+y > y+x:       # no need to convert to int because x+y and y+x are same length
                return -       # so lexicographic string sort behaves like numeric sort
            else:
                return 

        nums = list(map(str, nums))     # convert to strings
        nums.sort(key=functools.cmp_to_key(comparator))

        return nums
ls=[,,,,,]
x=Solution()
print(x.largestNumber(ls))

输出

['', '', '', '', '', '']
[Program finished]