#String Manipulation

Outline an approach to find the smallest valid substring that satisfies multiple conditions. Discuss edge cases such as empty inputs and large constraints.

Describe a method for optimizing a subarray traversal with a character frequency constraint. Consider the performance implications of your approach.

Complete three coding problems within 90 minutes. The topics include arrays, hashmaps, and string manipulation. Two problems are of medium difficulty, and one is hard.

Given a string, perform various manipulations while adhering to specific constraints. Discuss potential edge cases that could occur during this process.

Determine if a given string can become a palindrome by removing at most one character. Use the two-pointer technique to efficiently validate the condition in O(n) time.