边工作边刷题：70天一遍leetcode: day 4

Largest Number

要点：这题一开始肯定想怎么track每个number从大到小的每一位，这样就把自己绕进去了。正确的方法是把找largest number组合看成几个数的排序，关键是要如何比较两个数。

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.

class Solution:
    # @param {integer[]} nums
    # @return {string}
    def largestNumber(self, nums):
        def compare(a, b):
            return [1,-1][a+b>b+a]
        nums = [str(a) for a in nums]
        nums = sorted(nums, cmp = compare)
        return ''.join(nums).lstrip('0') or '0'