Leetcode 179. Largest Number

文章作者：Tyan
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1. Description

Largest Number

2. Solution

解析：这道题的关键在于想到需要编写一个比较函数来比较两个数字的“大小”，即两个数字排列的先后顺序。

• Version 1

import functools

class Solution:
    def largestNumber(self, nums):
        nums_str = [str(num) for num in nums]
        nums_str = sorted(nums_str, key=functools.cmp_to_key(self.compare), reverse=True)

        result = ''.join(nums_str)
        if result[0] == '0':
            return '0'
        else:
            return result


    def compare(self, x, y):
        s1 = x + y
        s2 = y + x

        if s1 > s2:
            return 1
        if s1 < s2:
            return -1
        return 0

• Version 2

import functools

class Solution:
    def largestNumber(self, nums):
        nums_str = list(map(str, nums))
        cmp = lambda x, y: 1 if x + y > y + x else -1 if x + y < y + x else 0
        nums_str = sorted(nums_str, key=functools.cmp_to_key(cmp), reverse=True)
        return str(int(''.join(nums_str)))

Reference

1. https://leetcode.com/problems/largest-number/