DP in LeetCode

Welcome to a focused journey into one of the most challenging and rewarding topics in competitive programming and technical interviews: Dynamic Programming. If you've ever felt intimidated by a LeetCode problem tagged "Dynamic Programming," this book is for you. It's not just a collection of solutions; it is a guided manual for learning how to think about and solve these complex problems using Python.

Dynamic Programming (DP) is more than just an algorithm; it's a powerful problem-solving technique. It's about breaking down seemingly impossible problems into manageable, overlapping subproblems and building up a solution. This book is designed to demystify that process. We will move beyond rote memorization and into the world of pattern recognition, recursive thinking, and algorithmic optimization that is the heart of DP.

Our adventure begins with the fundamentals: understanding how to approach a problem recursively. From there, we will explore the core concepts of memoization (top-down DP) and tabulation (bottom-up DP). You will see how a simple Python decorator, like @functools.lru_cache, can elegantly implement a powerful caching strategy, transforming a slow recursive function into a highly efficient DP solution. We won't just use these tools; we'll understand why they work.

This is a hands-on book. Each chapter is built around specific, well-known problems from LeetCode, crafted to teach a particular DP pattern or technique. We will dissect each problem, develop an intuition, and code the solution step-by-step. The path to mastering DP is paved with practice, and this book is designed to be your companion on that path.

Whether you are a student preparing for your first technical interview, a software engineer aiming to sharpen your algorithmic skills, or simply a curious programmer who wants to conquer a difficult topic, this book will equip you with the mental models and practical skills you need. My hope is that by the end of this journey, you will approach any dynamic programming problem with confidence and a clear strategy for finding the solution.

Let's begin.