Building an LRU Cache in TypeScript: Hash Map and Doubly Linked List in Practice
Build an LRU cache in TypeScript with a hash map and doubly linked list, then compare it with a simpler JavaScript Map implementation and O(1) operations.
Articles
Data Structures
Data structures are the shapes we choose to organise information so the surrounding code can work with it efficiently. The useful question is not how many structures you can name, but which access or update problem each one solves. That is why these articles overlap naturally with both Algorithms and LeetCode. This category is for the posts where the structure itself is a big part of the lesson, not just a background detail in the final solution.
Building an LRU Cache in TypeScript: Hash Map and Doubly Linked List in Practice. 
Union‑Find Explained: Solving the 'Number of Provinces' Problem. Union‑Find Explained: Solving the 'Number of Provinces' Problem
Solve Number of Provinces with union‑find in TypeScript, comparing DFS, connected components, path compression, union by rank, and matrix scanning.
LeetCode: The 'Kth Smallest Element in a BST' Problem. LeetCode: The 'Kth Smallest Element in a BST' Problem
Solve Kth Smallest Element in a BST with in‑order traversal, showing why the tree's ordering removes the need for a separate sorting step in interviews.
LeetCode: Finding the Diameter of a Binary Tree. LeetCode: Finding the Diameter of a Binary Tree
The diameter of a binary tree is the longest path between any two nodes. I'll explain clearly how we can solve this problem using recursion in JavaScript.
LeetCode: Solving the 'Merge Two Sorted Lists' Problem. LeetCode: Solving the 'Merge Two Sorted Lists' Problem
The 'Merge Two Sorted Lists' problem on LeetCode involves combining two sorted linked lists into one. Here, I explore a clear solution with TypeScript examples.
Monotonic Stack: Solving the 'Daily Temperatures' Problem. Monotonic Stack: Solving the 'Daily Temperatures' Problem
Solve Daily Temperatures with a monotonic stack in TypeScript, storing indices to find the next warmer day without repeated scanning and common mistakes.
Implementing a Trie in TypeScript: Solving 'Implement Trie (Prefix Tree)'. Implementing a Trie in TypeScript: Solving 'Implement Trie (Prefix Tree)'
Implement a Trie prefix tree in TypeScript with Map‑based nodes, insert, search, startsWith, shared prefixes, complexity, and alternative child storage.
Solving the LeetCode 'Binary Tree Zigzag Level Order Traversal' Problem. Solving the LeetCode 'Binary Tree Zigzag Level Order Traversal' Problem
Solve Binary Tree Zigzag Level Order Traversal with breadth‑first search, level sizing, alternating output order, and TypeScript implementation details.
Breadth‑First Search: Solving Binary Tree Level Order Traversal. Breadth‑First Search: Solving Binary Tree Level Order Traversal
Solve Binary Tree Level Order Traversal with breadth‑first search in TypeScript, using a queue, level sizing, edge cases, and cleaner iteration.
Prefix Sums and Hash Maps: Solving 'Subarray Sum Equals K'. Prefix Sums and Hash Maps: Solving 'Subarray Sum Equals K'
Solve Subarray Sum Equals K with prefix sums and a hash map in TypeScript, including negative numbers, count storage, and why sliding window fails.
Fast and Slow Pointers: Solving the 'Linked List Cycle' Problem. Fast and Slow Pointers: Solving the 'Linked List Cycle' Problem
Solve Linked List Cycle with fast and slow pointers in TypeScript, comparing visited‑node storage with Floyd's cycle detection and common mistakes.
LeetCode: Removing the nth Node from the End of a List. LeetCode: Removing the
nthNode from the End of a ListRemove the nth node from a linked list in TypeScript. Compare the two‑pass and pointer‑gap approaches, their edge cases, types and linear‑time complexity.
Add Two Numbers in TypeScript: A LeetCode Linked List Solution. Add Two Numbers in TypeScript: A LeetCode Linked List Solution
Solve LeetCode Add Two Numbers in TypeScript with linked‑list traversal, carry handling, edge cases, and a clear implementation you can test and extend.