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LeetCode 2516 · Solution & editorial
You are given a string s consisting of the characters 'a', 'b', and 'c' and a non-negative integer k. Each minute, you may take either the leftmost character of s, or the rightmost character of s.
Take K of Each Character From Left and Right is a Sliding Window problem, in the Variable Size (Condition-Based) subpattern. The pattern covers fixed-size, variable-size, and character frequency matching window techniques
Master variable-size sliding window for condition-based problems like longest substring without repeating characters.
The reference solution runs in O(n) time and O(1) space.
The full editorial is part of Pro
It explains the core insight, the complexity analysis and the common mistakes, with a worked solution.
Take K of Each Character From Left and Right is a Sliding Window problem, in the Variable Size (Condition-Based) subpattern. Once the approach above makes sense, write it yourself and then work through the neighbouring problems that reuse it.