list中的元素排列组合成最大的数

class Solution:    # @param {integer[]} nums    # @return {string}    def largestNumber(self, nums):        import itertools        a = list(itertools.permutations(nums,len(nums)))        d = []        for i in a:            str1 = ''            for j in i:                str1 += str(j)            d.append(int(str1))        return str(max(d))solution = Solution()print solution.largestNumber([1,2,3,4,5,6,7,8,9,0])