Two Sum & Hash-Map Lookup Pattern
Trade space for time using a hash map to convert O(n²) pair-finding into O(n) single-pass lookups. Foundation pattern behind dozens of LC problems.
Generalist software engineer track. Foundation: DSA mastery, CS fundamentals, coding-pattern bank, behavioral STAR stories tuned to the target company.
Primary categories: dsa · cs-fundamentals · behavioral
Trade space for time using a hash map to convert O(n²) pair-finding into O(n) single-pass lookups. Foundation pattern behind dozens of LC problems.
O(1) get/put cache with bounded capacity by combining a hash map (key → node) with a doubly linked list (recency). One of the most-asked LC mediums across Mag7.
Classic system-design starter. Tests capacity estimation, ID generation, read-heavy storage, caching, and analytics. Asked at Amazon, Microsoft, Uber, LinkedIn.
Structured story format used by every Mag7 behavioral round. Google extends to STAR-L (Learnings). Amazon expects 1 LP per story. Netflix tunes to culture pillars.