面试题 45. 把数组排成最小的数

输入: [10,2]
输出: "102"

输入: [3,30,34,5,9]
输出: "3033459"

import functools

class Solution:
    def minNumber(self, nums: List[int]) -> str:
        if not nums:
            return ''

        def compare(s1, s2):
            if s1 + s2 < s2 + s1:
                return -1
            if s1 + s2 > s2 + s1:
                return 1
            return 0

        return ''.join(sorted([str(x) for x in nums], key=functools.cmp_to_key(compare)))

class Solution {
    public String minNumber(int[] nums) {
        if (nums == null || nums.length == 0) {
            return "";
        }
        return Arrays.stream(nums).mapToObj(String::valueOf).sorted((s1, s2) -> (s1 + s2).compareTo(s2 + s1)).reduce((s1, s2) -> s1 + s2).get();
    }
}

/**
 * @param {number[]} nums
 * @return {string}
 */
var minNumber = function (nums) {
  nums.sort((a, b) => {
    let s1 = a + "" + b;
    let s2 = b + "" + a;
    if (s1 < s2) {
      return -1;
    } else return 1;
  });
  return nums.join("");
};