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$ curl repovive.com/roadmaps/meta-interview-prep-v2/coding-patterns-i-arrays-strings-stacks/lc-670-maximum-swap-implementation

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$ curl repovive.com/roadmaps/meta-interview-prep-v2/coding-patterns-i-arrays-strings-stacks/lc-670-maximum-swap-implementation

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LeetCode 670 Maximum Swap - Implementation - Coding Patterns I: Arrays, Strings & Stacks | Meta Interview Prep | Repovive

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LeetCode 670 Maximum Swap - Implementation

The code

Record the last position of each digit, then scan left to right for the first improvable position.

Here's the solution:

function maximumSwap(num):
    digits = list of digits of num
    last = array of size 10
    for i in range(len(digits)):
        last[digits[i]] = i
    for i in range(len(digits)):
        for d in range(9, digits[i], -1):
            if last[d] > i:
                swap digits[i] and digits[last[d]]
                return digits as number
    return num

$O(d)$ time, $O(d)$ space where $d$ is the number of digits (at most $9$ ).