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Day 9Easy
LeetCodeRelated practice
LeetCodeRelated practiceValid Palindrome (Alpha-Numeric Filter)
Two Pointers / FilteringSolved Oct 31, 2025
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LeetCodeRelated practiceTwo Pointers / FilteringSolved Oct 31, 2025
11 in the last 6 months
Community-reported company tags from leetcode-company-wise-problems (updated 2026-10-08). Bar shows how often each company asks it.
Problem
Given a string S, determine if it is a palindrome, considering only alphanumeric characters and ignoring case.
A palindrome is a word, phrase, or sequence that reads the same backwards as forwards.
Reading the solution first feels like progress, but it makes the next similar problem — and the interview version — much harder, because you skipped the part where you figure it out. Give it an honest 20–30 minutes. Stuck? Re-read the pattern, watch the concept video, or try the brute force first.
Hidden: approach · solution code
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