These are Data Structures questions of the kind Google actually asks — the patterns reported from Google's AI-engineering rounds, where design trade-offs, scale and failure modes matter as much as definitions. Treat this page as a mock interview: say every answer out loud before revealing it. If one surprises you, the lesson behind it is linked at the bottom.
Google Data Structures concept questions
Design a data structure supporting insert(x), delete(x) and getRandom() — all in O(1). getRandom must return a uniformly random stored element.
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How would you serialise a binary tree to a string and deserialise it back — exactly, including its shape?
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Google Data Structures applied & hands-on questions
Given a BST and k, return the k-th smallest value. Do it without collecting all n values, and state the complexity precisely.
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How to use this page: Google rarely asks something you've never seen — they ask a standard Data Structures concept and then push one level deeper ("why?", "what would you do if..."). Master the concept in the Data Structures course lessons, and the follow-up stops being scary.
Keep practising: Hash Tables, Linked Lists, Heaps and Choosing the Right Structure cover what most Google Data Structures rounds test.