leetcode Largest Number python

Largest Number

Given a list of non negative integers, arrange them such that they form the largest number.

For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

python code：

class Solution:
# @param num, a list of integers
# @return a string
def largestNumber(self, num):
　　num=[str(x) for x in num]
　　num.sort(cmp=lambda x, y: cmp(y+x, x+y))　　　　#字符串按ascii排序即可
　　return ''.join(num).lstrip('0') or '0'　　　　　　　　　　#输出时不显示左边的0