Solution: Longest Repeating Character Replacement

Statement

Given a string s and an integer k, find the length of the longest substring in s, where all characters are identical, after replacing, at most, k characters with any other lowercase English character.

Constraints:

• $1 \leq$ s.length $\leq 10^3$
• s consists of only lowercase English characters
• $0 \leq$ k $\leq$ s.length

Solution

So far, you’ve probably brainstormed some approaches and have an idea of how to solve this problem. Let’s explore some of these approaches and figure out which one to follow based on considerations such as time complexity and any implementation constraints.

Naive approach

The naive approach would be iterating over each character of the string to form all possible substrings. For each character, we explore all possible substrings starting from that position. Within each substring, we calculate the number of required replacements to make all characters identical using a nested loop. If the count is less than or ...