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DSA and system design, mapped.

Problems are infinite. Patterns are not. All 200 of them, arranged so you can see how they connect, plus 228 system design lessons that start from a system breaking and work out why. Animated diagrams, Java code, real numbers.

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New to DSALearn DSA from zero22 short lessons covering Big-O through dynamic programming, each with Java you can run.Start lesson 1→Interview soonSystem design course61 topics from CAP theorem to designing a chat system, split into short tutorials with diagrams.See the syllabus→Already practisingLook up a techniqueEvery pattern indexed by topic, with complexity, Java code, and the problems that use it.Browse the index→

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DSA Patterns18 topics · 200 techniques

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Prefer a list? Every topic below links to a full index of its patterns and techniques, each with Java code, complexity analysis, and interview tips.

Array String Hash Map Stack Queue / Deque Linked List Trees Recursion Heap Graphs Dynamic Programming Greedy Matrix Bit Manipulation Trie Sorting Range Structures Math & Number Theory

Also see:DSA·Learn DSA·All Techniques·Compare·DSA Cheatsheet·Java Cheatsheet·System Design Cheatsheet