Kotlin Data Structures

A focused collection of data structures implemented from scratch in Kotlin. Built for learning, interview preparation, and understanding the trade-offs behind the abstractions used every day.

Each implementation favors readable code, clear APIs, and tests that demonstrate expected behavior.

Linear data structures

• Dynamic arrays — resizable arrays and circular buffers.
• Linked lists — singly and doubly linked lists.
• Stacks — array-, linked-list-, and queue-backed stacks.
• Queues and deques — array-, linked-list-, and stack-backed queues, deques, and monotonic queues.

Hierarchical data structures

• Trees — tree nodes and traversal algorithms.
• Binary search trees — ordered trees and reconstruction.
• AVL trees — self-balancing binary search trees.
• Heaps — binary and d-ary min heaps.
• Union-find — path compression with union by rank or size.
• Binary indexed trees — efficient prefix-sum queries and updates.

Hashing

• Hash tables — separate chaining and linear-probing strategies.
• Hash sets — a map-backed set implementation.

String data structures

• Tries — prefix trees for string lookup.
• Suffix arrays — slow, medium, and optimized constructions, plus string-search problems.

Run the tests

./gradlew test

Inspired by William Fiset and Donglai Fu.