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.
Constraints:
0 <= num <= 10^8