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Stacks, Queues, Hash Tables & Heaps - Java Edition
Data Structures & Algorithms for AI-Era Interviews
This book is 100% completeLast updated on 2026-10-20
Stacks, Queues, Hash Tables & Heaps - Java Edition teaches 50 algorithms built on stacks, queues, hash tables, and heaps through plain-language explanations, Java implementations, and step-by-step visual walkthroughs, all in full color.
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About
About the Book
Stop memorizing container tricks. Start seeing why they work.
Stacks, Queues, Hash Tables & Heaps - Java Edition teaches 50 algorithms built on stacks, queues, hash tables, and heaps through plain-language explanations, Java implementations, and step-by-step visual walkthroughs. A primer for each structure, a pattern map, and four AI-Era Interview Challenges build the instincts these problems rely on. Every algorithm is shown in full color, so every push, pop, bucket, and sift stands apart at a glance and is easy to trace.
Watch a stack parse an expression one token at a time. Follow a queue as a window slides across the input. See keys land in hash buckets and collisions chain together, and track a heap as it sifts the smallest value to the top. Instead of holding every intermediate step in your head, follow the execution on the page.
The visual walkthroughs use small multiples, a data visualization technique that presents successive stages of an algorithm as a series of consistently structured diagrams. By seeing meaningful stages together, you can compare states, follow what moves, and understand how each decision affects the next. This brings the algorithm to life, reinforcing understanding and helping the underlying patterns and mechanics stay with you longer.
Every main algorithm is presented in three complementary parts:
Understanding & Reasoning: Learn the goal, key idea, edge cases, and time and space complexity before studying the implementation.
Inspect & Debug: Examine Java code alongside an AI-Era Interview Lens that challenges you to question assumptions, recognize plausible mistakes, and explain why a solution is correct.
Trace & Walkthrough: Follow the input through intermediate states to the result, with visual explanations of the decisions that matter.
The four pattern families cover Stacks & Expression Parsing; Queues & Sliding Windows; Hash Tables & Map Design; and Heaps & Priority Queues.
A stack, a queue, a hash table, and a heap all look like simple containers, right up until the order things come out of them decides whether your answer is right. This book is about seeing that order before you write a single line of code.
Every code sample was compiled, tested against edge cases beyond what's printed on the page, and independently reviewed before making it into the book.
Designed for readers with basic Java knowledge who want to strengthen coding interview preparation, debugging, and algorithmic reasoning.
Understand the idea. Follow the state. Explain the result.
Author
About the Author
Flannan P. Brody
Flannan P. Brody is a software engineer with over 18 years of experience building large-scale systems at companies including Google, Apple, Disney+, and Genentech. A graduate of the Dublin Institute of Technology, he has navigated the high-stakes technical interview loops of the world's most selective tech companies more times than he'd care to admit.
Learn Algorithms Visually was born directly from those repeated cycles. Every return trip to the interview circuit brought a deeper layer of clarity, stripping away academic abstraction to reveal how algorithms actually function under the hood. This series is his attempt to compress years of hard-won insight into a single, intuitive pass.
When he isn't writing or architecting code, he's usually playing soccer or traveling.
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