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Optimize with a cache/hash map

Last updated: Mar 29, 2026

Quick Overview

This question evaluates a candidate's competency in designing and analyzing in-memory cache/hash map optimizations, covering cache key/value selection, eviction policy and invalidation strategies, concurrency safety, and time and space complexity before and after caching.

  • Medium
  • Amazon
  • Coding & Algorithms
  • Software Engineer

Optimize with a cache/hash map

Company: Amazon

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: Medium

Interview Round: Technical Screen

Propose and analyze an optimization that uses an in-memory cache/dictionary/hash map to speed up repeated lookups in the script (e.g., mapping file paths or parsed license strings to computed results). Specify cache keys and values, eviction policy (LRU/LFU/TTL), and invalidation when the underlying file changes (mtime/hash). Discuss concurrency safety if multiple processes/threads may run; provide pseudocode for get/put with validation; and state expected time and space complexity before and after introducing the cache.

Quick Answer: This question evaluates a candidate's competency in designing and analyzing in-memory cache/hash map optimizations, covering cache key/value selection, eviction policy and invalidation strategies, concurrency safety, and time and space complexity before and after caching.

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Amazon
Sep 6, 2025, 12:00 AM
Software Engineer
Technical Screen
Coding & Algorithms
1
0

Propose and analyze an optimization that uses an in-memory cache/dictionary/hash map to speed up repeated lookups in the script (e.g., mapping file paths or parsed license strings to computed results). Specify cache keys and values, eviction policy (LRU/LFU/TTL), and invalidation when the underlying file changes (mtime/hash). Discuss concurrency safety if multiple processes/threads may run; provide pseudocode for get/put with validation; and state expected time and space complexity before and after introducing the cache.

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