Nil Pointers: DS&A Posts

The cold email that got me into a PhD
My PhD origin story.
June 7, 2026ResearchDS&A
Toolkit-X: A better way to do DS&A problem lists
Introducing Toolkit-X: a free DS&A toolkit with curated BCtCI problems that can be used like a traditional problem list.
December 11, 2025BCtCIDS&A
In Defense of Coding Interviews
An argument in favor of DS&A interviews.
October 27, 2025DS&A
BCtCI Chapter: Set & Map Implementations
Learn how sets & maps are built from scratch, and refine your knowledge of hashing.
September 28, 2025BCtCIDS&A
BCtCI Chapter: Monotonic Stacks & Queues
Learn how monotonic stacks and queues are two sides of the same idea and how to leverage them in interviews!
September 27, 2025BCtCIDS&A
Counting Islands in a Grid: DFS or BFS?
A deeper look at this classic grid problem - including some beautiful fractals that unexpectedly appear in the BFS analysis.
September 26, 2025DS&A
Building Lego castles with recurrences, memoization, and math
A walk through recurrences, memoization, and math tricks -- via Lego castles.
September 25, 2025BCtCIDS&A
BCtCI Free Resources
A comprehensive list of all free resources available from Beyond Cracking the Coding Interview, including chapters, problems, tools, and templates.
August 8, 2025BCtCIDS&A
BCtCI Chapter: Union-Find
Learn how this fascinating data structure speeds up graph-related operations.
August 6, 2025BCtCIDS&A
Top-K Problems: Sorting vs Heaps vs Quickselect
The different approaches to finding the k smallest/largest elements in an array.
July 31, 2025BCtCIDS&A
Queues in JS interviews
JS doesn't have built-in queues, which can be an issue if you have to implement a BFS. Here are the workarounds.
July 30, 2025BCtCIDS&A
Get Binary Search Right Every Time, Explained Without Code
A binary search recipe that works for every problem, explained without code.
April 15, 2025BCtCIDS&A
Problem Solving BCtCI Style
A problem walkthrough using the concepts from Beyond Cracking the Coding Interview.
March 19, 2025BCtCIDS&A
Heapify Analysis Without Math
A proof that heapify takes linear time without using complex equations.
October 30, 2024BCtCIDS&A
Lazy vs Eager Algorithms
Exploring the tradeoffs between lazy and eager implementations of common algorithms.
October 16, 2024DS&A
Actually Implementing Dijkstra's Algorithm
A comprehensive guide to different implementations of Dijkstra's algorithm, with code.
June 22, 2020DS&A
Reachability Problems and DFS
An extensive list of questions that can be solved with DFS.
June 21, 2020DS&A
Breaking Down Dynamic Programming
A step-by-step guide to understanding and implementing dynamic programming algorithms with practical examples.
February 5, 2020DS&A
Iterative Tree Traversals: A Practical Guide
A guide to implementing preorder, inorder, and postorder tree traversals iteratively.
February 4, 2020DS&A