###### tags: `Leetcode` `medium` `math` `python`

# 670. Maximum Swap

## [題目連結:] https://leetcode.com/problems/maximum-swap/

## 題目:
You are given an integer ```num```. You can swap two digits at most once to get the maximum valued number.

Return the maximum valued number you can get.

**Example 1:**

Input: num = 2736
Output: 7236
Explanation: Swap the number 2 and the number 7.

**Example 2:**

Input: num = 9973
Output: 9973
Explanation: No swap.

## 解題想法:
* 要求可以任兩數交換位置一次(也可以不交換)，使得num最大
* 暴力法:雙for迴圈，每個位置都交換，選出最大的

## Python:

class Solution(object):
    def maximumSwap(self, num):
        """
        :type num: int
        :rtype: int
        """
        nums= list(str(num))
        res=num
        for i in range(len(nums)-1):
            for j in range(i+1,len(nums)):
                nums[i],nums[j]=nums[j],nums[i]
                res=max(res,int("".join(val for val in nums)))
                nums[i],nums[j]=nums[j],nums[i]
        return res

result=Solution()
ans=result.maximumSwap(num = 2736)
print(ans)