juniorHeaps and Maps
What is the difference between HashMap and TreeMap?
Updated Apr 28, 2026
Short answer
HashMap is O(1) average but unordered; TreeMap is O(log N) and sorted.
Deep explanation
Heaps and Maps are fundamental for optimization. HashMap is O(1) average but unordered; TreeMap is O(log N) and sorted. Heaps are used for priority management, while Maps provide constant-time data retrieval.
Real-world example
Priority queues in operating systems.
Common mistakes
- Confusing a Heap with a sorted array.
Follow-up questions
- Is a Heap a sorted structure?