This assessment verifies the Specialized Structures and Production DSA module. Passing it contributes up to 15 points in the 86-100 score band.
Questions
8
Limit
120m
Pass
85%
Score
+15
13 pts
A command palette has 8,000 mostly static commands and must show up to 5 suggestions after each keystroke. Compare a trie with a sorted array plus binary search. Which would you choose first, and what would make you switch?
14 pts
Design `WordDictionary` with `addWord(word)` and `search(pattern)` where `.` matches any single character. Explain how the wildcard changes trie search complexity.
14 pts
A revenue dashboard answers arbitrary date-range sum queries. Historical data is corrected thousands of times per hour. A teammate proposes prefix sums because range queries become O(1). Review the proposal and choose a structure.
12 pts
A mutable range-sum implementation updates the leaf value in a segment tree but does not recompute ancestor nodes. The tests pass for single-index queries but fail for wider ranges. Review the bug and state the invariant.
13 pts
A team wants to store product permissions as a single integer bitmask instead of a set of strings. Give a production-grade argument for and against this change.
9 pts
Every integer in an array appears exactly twice except one integer that appears once. Which explanation best justifies the O(1)-space XOR solution?
15 pts
Design an LRU cache with `get` and `put` in O(1) average time. Name the two cooperating structures and explain eviction behavior.
15 pts
A feed service uses one append-only array for ordered rendering, duplicate prevention, item lookup by ID, ranking, and old-item search. It works for prototypes but is now slow and hard to change. Review the design and propose a production DSA decomposition.