670. Maximum Swap

Given a non-negative integer, you could swap two digits at most once to get the maximum valued number. Return the maximum valued number you could get.

Example 1:

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

Example 2:

Input: 9973
Output: 9973
Explanation: No swap.

Note:

1. The given number is in the range [0, 108]

class Solution {
public:
    int maximumSwap(int num) {
        int maxid = -1;
        int maxdigit = -1;
        int leftidx = -1;
        int rightidx = -1;
        string number = std::to_string(num);
  
        for(int i=number.size()-1; i>=0; i--)
        {
            if(number[i] > maxdigit)
            {
                maxid = i;
                maxdigit = number[i];
                continue;
            }
            
            if(number[i] < maxdigit)
            {
                leftidx = i;
                rightidx = maxid;
            }
        }
        
        if(leftidx == -1) return num;
        
        std::swap(number[leftidx], number[rightidx]);

        return std::stoi(number);
        
    }
};

python:

class Solution(object):
    def maximumSwap(self, num):
        """
        :type num: int
        :rtype: int
        """
        number=str(num)
        length=len(number)
        maxid=-1
        maxNumber=-1
        leftid=-1
        rightid=-1
        for i in range(length-1,-1,-1):
            if number[i] > maxNumber :
                maxid = i
                maxNumber = number[i]
                continue
            if number[i] < maxNumber :
                leftid = i
                rightid = maxid
        
        if leftid == -1 : return num
        list_number = list(number)
        tmp = list_number[leftid]
        list_number[leftid] = list_number[rightid] 
        list_number[rightid] = tmp
        str_number = ''.join(list_number)
        return int(str_number)