These are Data Structures questions of the kind Amazon actually asks — the patterns reported from Amazon'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.
Amazon Data Structures concept questions
Two linked lists merge at some node and share their tail (a Y shape). Find the intersection node in O(m + n) time and O(1) space.
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Amazon Data Structures applied & hands-on questions
Implement an LRU cache with get(key) and put(key, value), both O(1), evicting the least-recently-used entry when capacity is exceeded. (In an interview, code it; here, Python's OrderedDict shows the structure.)
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Each node has next and an arbitrary random pointer to any node (or None). Deep-copy the list. Give the O(n)-space solution, then the O(1)-space interleaving trick.
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How to use this page: Amazon 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 Amazon Data Structures rounds test.