Decode String: which companies ask it and how to practise

Decode String is a Medium problem that 40 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 Decode String?

Public company lists attribute Decode String, a Medium problem, to 40 companies. The most frequent askers are Flexport, Tencent and Zoho. 9 reports are from the last six months. It mainly tests string, stack and recursion. Use this as a practice guide, not a promise.

Practise this kind of question aloud

Who asks Decode String

40 companies appear in the public lists for this question. By how often each is reported: Flexport (very often), Tencent (very often), Zoho (very often), Coupang (very often), Yelp (very often), Tinkoff (very often), Roku (very often), razorpay (very often), Compass (very often) and Wix (very often), and 30 more. 9 of them were reported in the last six months, Zoho, Zopsmart 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 Decode String tests

It is rated Medium, which is the level most interviews are built around: expect to talk through two approaches, pick one, code it cleanly, and answer a cross-question on an edge case or a change to the constraints.

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.

A stack fits anything that closes in reverse order: brackets, nested calls, the nearest previous or next larger value. Say what the stack holds at each step.

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

Questions to practise next

If you can solve Decode String, 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 Valid Anagram (Easy). Each has its own page in the questions list.

Frequently asked questions

Is Decode String asked at Amazon?

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

How hard is Decode String?

Do I need to memorise the solution?

No. Interviewers listen for how you reason: the approach, the trade-offs, the edge cases and the complexity. Practise explaining it, not reciting it.

Sources and review date

Last reviewed 25 October 2026 Statements about other products come from their own public pages: