To prove safety Offer (32): the smallest number arranged in an array

To prove safety Offer (32): the smallest number arranged in an array

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First, the primer

This series is my brush "to prove safety Offer" brush off the cattle in question notes online, it aims to enhance the ability under its own algorithm.
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Second, the title

Enter a positive integer array, the array of all the numbers arranged in a number spliced ​​together, the splice can print out all numbers smallest one. 3,32,321 input array} {e.g., print the minimum number of three numbers can be arranged to 321,323.

1, ideas

Encounter this problem, of course, the whole arrangement can be done, but time complexity is O (n!). Here we define ourselves a rule, after a string of splicing were compared.

Sort rules are as follows:

If ab> ba then a than b, that example: a = 3 b = 32 ab = 332 ba = 323 so that a is greater than b following rules and consistent with this comparison method
if ab <ba is a is smaller than b,
if ab = ba is a equal to B;

According to the rules above, we first need to be converted into a digital string then compared, because of the need to string together for comparison. After completion of the comparison, to output sequentially.

2, programming

python

Code implementation:

# -*- coding:utf-8 -*-
class Solution:
    def PrintMinNumber(self, numbers):
        # write code here
        if numbers is None:
            return ""
        lens = len(numbers)
        if lens ==0 :
            return ""
        tmpNumbers = sorted(numbers,cmp=self.compare)
        return int(''.join(str(x)for x in tmpNumbers))
    def compare(self,num1,num2):
        t = str(num1)+str(num2)
        s = str(num2)+str(num1)
        if t>s:
            return 1
        elif t<s:
            return -1
        else:
            return 0

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