Regular Expression Matching: which companies ask it and how to practise

Regular Expression Matching is a Hard problem that 22 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 Regular Expression Matching?

Public company lists attribute Regular Expression Matching, a Hard problem, to 22 companies. The most frequent askers are Netskope, X and Rokt. 5 reports are from the last six months. It mainly tests string, dynamic programming and recursion. Use this as a practice guide, not a promise.

Practise this kind of question aloud

Who asks Regular Expression Matching

22 companies appear in the public lists for this question. By how often each is reported: Netskope (very often), X (very often), Rokt (very often), Zoho (very often), Waymo (often), Coupang (often), Airbnb (often), ByteDance (often), Sprinklr (often) and PhonePe (often), and 12 more. 5 of them were reported in the last six months, Amazon, Bloomberg and Google 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 Regular Expression Matching tests

It is rated Hard, so a correct brute force with a clear path to the better idea is a good result; interviewers watch how you reason when the answer is not obvious and how you use their hints.

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.

Dynamic programming is solving a problem from the answers to smaller copies of itself. Start with the plain recursion, find the repeated states, then store them; explain what the state means before you write any table.

Recursion needs a base case, a smaller call, and a clear picture of the stack. Say the depth and whether you could do it iteratively.

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/regular-expression-matching/ (opens the publisher's page). The statement is theirs; we do not reproduce it.

Questions to practise next

If you can solve Regular Expression Matching, try these next, chosen because they share its main topic and many of the same companies: Valid Parentheses (Easy), Longest Substring Without Repeating Characters (Medium), Group Anagrams (Medium), Longest Palindromic Substring (Medium), Longest Common Prefix (Easy) and Decode String (Medium). Each has its own page in the questions list.

Frequently asked questions

Is Regular Expression Matching asked at Amazon?

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

How hard is Regular Expression Matching?