680. Valid Palindrome II

Srinivas Vaddi
2 min readApr 29, 2024

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You can find this on LeetCode here , solution is here, and understand the logic here!

Thoughts and Talk

Palindromes have stood the test of time as a classic interview question due to their fundamental nature. Although there are various approaches to solving them, the traditional two-pointer method remains the simplest. However, in this current referenced leetcode problem there’s a twist to this problem❗ -it’s not just about determining if a string is a palindrome. The real challenge lies in identifying whether removing one character from the string would transform it into a palindrome.

This added complexity makes the question intriguing, even if it’s categorized as easy. It requires a keen eye for detail and a thorough understanding of palindrome properties to solve effectively.

The problem of determining if a string can be transformed into a palindrome by removing at most one character introduces a fascinating twist on a classic problem. This task isn’t just about palindrome detection; it also tests our ability to handle slight modifications in string properties efficiently. It’s a problem that requires not just understanding basic string manipulation but also a deeper insight into decision-making processes in algorithms.

Problem Statement

We need to determine whether a given string can be rendered a palindrome by deleting at most one character. This problem extends the classic palindrome check by adding the possibility of minor adjustments, presenting an interesting challenge in algorithm design.

Hints

  1. Utilize two pointers to compare characters from the beginning and end of the string.
  2. Upon finding non-matching characters, decide whether skipping the current character from the beginning or the end might help.
  3. Only one such skip is allowed. If skipping doesn’t help, the answer should be false.

Approaches Explored

Approach 1: Two-pointer with single skip check

Pros:

  • Efficient, since it typically requires scanning the string at most twice.
  • Simple to implement using conditional checks to handle the single allowed skip.

Cons:

Approach 2: Modified two-pointer with state tracking (not so different!)

This is the approach reflected in our original code. ouIt uses a breaker variable to handle complex decision points when both characters to the left and right could potentially be skipped to maintain a palindrome.

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Srinivas Vaddi
Srinivas Vaddi

Written by Srinivas Vaddi

Striver by nature, Developer by profession, Philosopher at mind, Writer by Virtue, passionate about everything!

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