剑指offer 把数组排成最小的数

题目

输入一个正整数数组，把数组里所有数字拼接起来排成一个数，打印能拼接出的所有数字中最小的一个。例如输入数组{3，32，321}，则打印出这三个数字能排成的最小数字为321323。

思路

排序算法，如果$num1+num2<num2+num1$，则$num1$排在$num2$左边。

代码

# -*- coding:utf-8 -*-
class Solution:
    def cmp(self, leftNum, rightNum):
        return int(str(leftNum) + str(rightNum)) > int(str(rightNum) + str(leftNum))
    def partition(self, numbers, left, right):
        leftIndex = left
        tmp = numbers[left]
        while left <= right:
            while left <= right and not self.cmp(numbers[left], tmp): left += 1
            while left <= right and self.cmp(numbers[right], tmp): right -= 1
            if left <= right: numbers[left], numbers[right] = numbers[right], numbers[left]
        numbers[leftIndex], numbers[right] = numbers[right], numbers[leftIndex]
        return right
    def qsort(self, numbers, left, right):
        if left < right:
            part = self.partition(numbers, left, right)
            self.qsort(numbers, left, part - 1)
            self.qsort(numbers, part + 1, right)
    def PrintMinNumber(self, numbers):
        # write code here
        if not numbers: return ""
        self.qsort(numbers, 0, len(numbers) - 1)
        tmp = [str(num) for num in numbers]
        return int(''.join(tmp))