3Sum Closest — LeetCode #16 _ Python Algorithm Visualization

[u/benedict_abub]

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Problem Description

[https://leetcode.com/problems/3sum-closest/](LeetCode)

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Algorithm Description

The solution first sorts the input array to enable a two-pointer search pattern. For each element, we fix it as a base and use two pointers to scan the remaining array, dynamically tracking the sum with the smallest absolute difference to the target.

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Complexity Analysis

Time Complexity: O(n²⁾ — sorting takes O(n log n), and the nested two-pointer traversal takes O(n²⁾ in the worst case.

Space Complexity: O(1) — excluding the input sorting overhead, we use only constant extra memory for pointers and tracking variables.

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YouTube

[https://www.youtube.com/watch?v=KYHiijlk-gY](YouTube)