Group Shifted Strings
A medium-tier problem at 67% community acceptance, tagged with Array, Hash Table, String. Reported in interviews at Wix and 2 others.
Group Shifted Strings is the kind of problem that looks simple until you realize you're building the wrong mental model. You get a list of strings and need to group those with the same shift pattern together. Google, Meta, and Wix have all asked this one. The pattern trick isn't hard once you see it, but the grouping logic trips candidates who try to hash the strings directly instead of their difference signatures. With a 67% acceptance rate, it's not a gimme, but it's not a wall either. If this lands in your assessment and you freeze on how to represent the pattern, StealthCoder solves it invisibly in seconds.
Companies that ask "Group Shifted Strings"
Group Shifted Strings is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too.
Get StealthCoderThe core insight is that two strings belong in the same group if consecutive character pairs have the same differences. For example, 'abc' and 'bcd' both have a difference sequence of [1, 1]. The obvious trap is trying to group strings by their content. Instead, compute the shift pattern (difference between each adjacent pair of characters), convert it to a hashable key, and use a hash table to bucket strings by that key. Most candidates get the algorithm right but overcomplicate the key generation or waste time on string manipulation. The pattern matching itself is straightforward once you stop thinking about the strings and start thinking about their deltas. StealthCoder handles the edge cases and key encoding so you don't blank on the exact format during the live OA.
Pattern tags
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Group Shifted Strings recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Group Shifted Strings interview FAQ
What's the actual trick to this problem?+
Stop comparing strings directly. Convert each string to its shift signature (the differences between consecutive characters). Two strings group together if they have identical signatures. Use a hash table keyed by that signature. That's the whole pattern. Most candidates understand it once they see the insight, but don't figure it out from scratch under time pressure.
Is Group Shifted Strings still asked at top companies?+
Yes. Google, Meta, and Wix have all reported it. It's a solid medium-difficulty screening question because it tests whether you can recognize a grouping problem and design a hash key, not brute-force pattern matching. It's not as common as Two Sum, but common enough to drill.
What's the edge case that bites people?+
Strings with length 1 have no differences, so they all group together. Make sure your difference sequence handles single characters. Also, wrapping around the alphabet (z to a) trips some candidates. If your language uses modulo, be careful with negative differences.
How does this relate to hash table topics?+
This is a canonical hash table grouping problem. You're using the table not just for lookup, but as a multimap to collect values under a derived key. The Array and String parts are setup. The real skill being tested is designing a good hash key, which is table fundamentals.
What's the time and space complexity?+
Time is O(n * k) where n is the number of strings and k is the average length (you compute differences for each string once). Space is O(n * k) for storing the result and hash table. It's linear and tight. No tricks to optimize further unless the input structure changes.
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