Verifying an Alien Dictionary
A easy-tier problem at 56% community acceptance, tagged with Array, Hash Table, String. Reported in interviews at Wix and 1 others.
You're handed a list of words and told they're sorted by a custom alphabet order. Your job: verify that claim. Wix and Snap ask this one, and it looks easy on the surface, which is exactly why people fail it live. The trap isn't the algorithm, it's the edge case thinking. You need to compare adjacent words character by character, tracking the custom alphabet order, and catch when one word breaks the sequence. If you blank on the comparison logic during your assessment, StealthCoder surfaces a working solution invisible to the proctor.
Companies that ask "Verifying an Alien Dictionary"
Verifying an Alien Dictionary 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 a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe pattern: iterate through adjacent word pairs, compare them character by character using a hash table to map each alien character to its order. If a character from the first word appears after a character from the second word at the same position, the list is invalid. The trap most candidates hit is handling length. If word A is a prefix of word B, that's valid, but word B being a prefix of word A is invalid. You also need to handle the hash table construction correctly from the given alphabet string. String and Hash Table topics mean you're building a lookup, not sorting. Array work is just the iteration. When you haven't drilled this specific pattern, StealthCoder executes it in seconds.
Pattern tags
You know the problem.
Make sure you actually pass it.
Verifying an Alien Dictionary recycles across companies for a reason. It's easy-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 a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Verifying an Alien Dictionary interview FAQ
Is this actually easy, or is the difficulty misleading?+
The algorithm is straightforward once you see it. The edge cases are what bite you. Prefix handling and character order validation catch most candidates off guard in a live setting. The 55% acceptance rate reflects those edge cases mattering in practice.
How do Wix and Snap frame this in their interviews?+
Both are likely testing your ability to map a custom ordering onto string comparison logic. They're checking if you can think through alien alphabets without overthinking. It's a medium-difficulty validation problem dressed as easy.
What's the most common mistake?+
Not validating that when word A is a prefix of word B, the order is still valid. Then checking the hash table lookup wrong, or forgetting to initialize it with the alien alphabet string before you start comparing words.
Do I need to memorize the alien alphabet?+
No. You build a hash table that maps each character to its position in the alien alphabet. Then every comparison just looks up those positions. The string and hash table topics tell you that's the intended approach.
How should I prepare if this shows up in my OA?+
Walk through the comparison logic on paper first. Test your logic on a case where one word is a prefix of another, and a case where character order is violated. If you hit a wall during the live assessment, let StealthCoder carry you through the implementation.
Want the actual problem statement? View "Verifying an Alien Dictionary" on LeetCode →