第一种做法

• 长度不一的时候，用短的元素的前缀填补到短元素的后面，然后比较；
• 若一直相等，做相加的数值比较；

from functools import cmp_to_key
#letterlist.sort(key=cmp_to_key(keyL))
class Solution(object):
    def printMinNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: str
        """
        def func(x, y):
            if len(x) > len(y):
                t = y[:] + y[:len(x) - len(y)]
                for i, j in zip(x, t):
                    if i > j:
                        return 1
                    elif i < j:
                        return -1
                xt, tx = int(x + y), int(y + x)
                if xt > tx:
                    return 1
                elif xt < tx:
                    return -1
                return 0
            elif len(x) <= len(y):
                t = x[:] + x[:len(y) - len(x)]
                for i, j in zip(t, y):
                    if i > j:
                        return 1
                    elif i < j:
                        return -1
                ty, yt = int(x + y), int(y + x)
                if ty > yt:
                    return 1
                elif ty < yt:
                    return -1
                return 0
        nums = sorted(list(map(str,nums)), key = cmp_to_key(func))
        return "".join(map(str, nums))

优化第一种方法直接拼接进行比较

from functools import cmp_to_key
class Solution(object):
    def printMinNumber(self, nums):
        """ 
        :type nums: List[int]
        :rtype: str
        """
        def func(x, y):
            t, g = x + y, y + x
            for i, j in zip(t, g):
                if i > j:
                    return 1
                elif i < j:
                    return -1
            return 0
        nums = sorted(list(map(str,nums)), key = cmp_to_key(func))
        return "".join(map(str, nums))