Valid Palindrome: which companies ask it and how to practise

Valid Palindrome is a Easy problem that 37 companies are reported to ask. This page shows who, how often and how recently, what the question tests, and how to practise it out loud with an interviewer who asks follow-ups. We link to the original problem statement instead of copying it.

Which companies ask Valid Palindrome?

Public company lists attribute Valid Palindrome, a Easy problem, to 37 companies. The most frequent askers are Cadence, Zenefits and LTI. 11 reports are from the last six months. It mainly tests two pointers and string. Use this as a practice guide, not a promise.

Practise this kind of question aloud

Who asks Valid Palindrome

37 companies appear in the public lists for this question. By how often each is reported: Cadence (very often), Zenefits (very often), LTI (very often), Comcast (very often), Meta (very often), HCL (very often), VK (very often), Yandex (often), Apple (often) and Fidelity (often), and 27 more. 11 of them were reported in the last six months, Meta, Apple and Bloomberg among them.

These are candidate reports collected in public lists, not statements from the companies. They are a good guide to what to practise and a poor guide to what you will be asked: interviewers change questions, and the same company asks different questions by team and level. Last reviewed 25 October 2026.

What Valid Palindrome tests

It is rated Easy, so interviewers expect a correct, complete solution and a clear statement of the time and space cost, often in the first 15 to 20 minutes, with time left for a variation.

Two pointers walk a sorted or symmetric structure from both ends, or one fast and one slow. The proof that you never skip the answer is what the interviewer is waiting for.

String problems test careful index handling and knowing which characters you may assume. Say out loud whether the input is ASCII, whether case matters, and what an empty string should return.

How to practise it

Do not just solve it silently. In a real interview you explain the approach before you code, write while you talk, and defend the solution to follow-ups. Set a timer, say the brute force and its cost first, then improve it, and finish by stating the time and space complexity and two edge cases you tested.

On giveinterview you can take this kind of question as a spoken interview: the AI interviewer opens with the problem, watches you code, asks cross-questions and ends with a scorecard. Your first 3 single-question interviews are free for life, every interview report is free, and a new account also gets 6 welcome credits.

Read the original statement here: https://leetcode.com/problems/valid-palindrome/ (opens the publisher's page). The statement is theirs; we do not reproduce it.

Questions to practise next

If you can solve Valid Palindrome, try these next, chosen because they share its main topic and many of the same companies: Longest Palindromic Substring (Medium), Trapping Rain Water (Hard), Container With Most Water (Medium), 3Sum (Medium), Find Median from Data Stream (Hard) and Move Zeroes (Easy). Each has its own page in the questions list.

Frequently asked questions

Is Valid Palindrome asked at Amazon?

Amazon appears in the public lists for Valid Palindrome, reported often. Treat that as a reason to practise it, not a promise you will be asked it.

How hard is Valid Palindrome?