Description

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.

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Example 1:

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

Input: num = 9973
Output: 9973
Explanation: No swap.
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Constraints:
0 <= num <= 108

Approach

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class Solution:
    def maximumSwap(self, num: int) -> int:
        result = num
        num_list = list(str(num))
        max_idx = -1

        for i in range(len(num_list)-1,-1,-1):
            if num_list[i] > num_list[max_idx]:
                max_idx = i
            else:
                num_list[i], num_list[max_idx] = num_list[max_idx], num_list[i]
                result = max(result,int("".join(num_list)))
                num_list[i], num_list[max_idx] = num_list[max_idx], num_list[i]
        
        return result

# Example usage:
num = 2736
solution = Solution()
print(f"The maximum valued number after at most one swap is: {solution.maximumSwap(num)}")