Advanced Data Structures and Implementation Questions

Deep and practical expertise in advanced data structures, their implementation details, performance characteristics, and selection for both algorithmic problems and production systems. Topics include arrays and dynamic arrays, strings, linked lists, stacks and queues, hash tables, heaps and priority queues, various tree forms including binary search trees and balanced trees, tries or prefix trees, segment trees and binary indexed trees or fenwick trees, union find or disjoint set union, suffix arrays, and advanced graph representations. Candidates should be able to implement core structures from first principles, demonstrate interfaces and invariants, reason about insertion deletion search traversal and iteration costs including worst case average case and amortized analysis, and discuss memory management and ownership in low level languages such as C and C plus plus as well as safe memory and reference use in managed languages. Evaluation also covers trade offs between contiguous and pointer based layouts, cache friendliness, concurrency considerations, selection of structures based on access patterns update frequency and memory constraints, handling of edge cases, testing and performance tuning for realistic inputs, and applying structures to problems such as top K queries prefix search connectivity range queries caches and union operations.

MediumTechnical

84 practiced

You inherit a service that uses linked lists to maintain millions of small elements. Production shows high tail latency and long GC pauses. As SRE, outline steps to diagnose, measure, and propose data-structure changes to reduce latency. Include migration and rollback strategy that minimizes customer impact.

HardTechnical

89 practiced

Design a tiered index that keeps hot prefixes in an in-memory compressed trie and cold prefixes on SSD as sorted blocks. Requirements: latency SLA for hot queries < 10ms. Discuss when to promote/demote prefixes, eviction policies, consistency between tiers, and recovery after crashes.

HardTechnical

66 practiced

Implement suffix array construction using prefix-doubling (O(n log n)) in C++. Given a string s, return the suffix array as indices. Focus on stable sorting by rank pairs, memory-efficient rank arrays, and explain how you would adapt this for large alphabets or integer arrays.

HardTechnical

71 practiced

Your team must pick between an in-house C++ lock-free queue implementation and using a widely used OSS concurrent-queue library. SLOs require minimal tail latency and low maintenance burden. How do you evaluate, benchmark, and decide? Describe criteria, experiments, and a safe rollout strategy.

MediumTechnical

72 practiced

Implement a segment tree in C++ that supports point updates and range-sum queries on an integer array of size n. Provide functions: build(vector<int>&), update(index, newValue), and query(left, right). Discuss iterative vs recursive implementations and memory layout decisions for production use.

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