[leetcode sort]179. 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.

对一组数字排序，使其组成的数字最大

思路：排序，不过重新定义排序规则，比如字符串x和字符串y，比较x+y和y+x的大小,如果x+y>y+x，则x>y

class Solution:
    def largestNumber(self, nums):
        nums = [str(n) for n in nums]
        nums.sort(cmp=lambda y,x:cmp(x+y,y+x))
        return ''.join(nums).lstrip('0') or '0'