the course

Pick up where you left off

Go in order if you are new — every chapter builds on the ones before it. Already comfortable? Jump straight to a track.

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just starting — that's the hardest step

0/38 chapters · 0/343 problems

Java for DSA

Write and debug the Java that DSA interviews actually need, without fighting the language.

  1. 01 What Happens in Memory
  2. 02 Arrays & Strings in Java
  3. 03 OOP for DSA & Design Rounds
  4. 04 Fast I/O, Judges & Debugging
  5. 05 Java Toolkit & Collections

Thinking tools

Approach any unseen problem calmly, measure code with Big-O, and think recursively.

  1. 06 Mindset & Problem Solving
  2. 07 Big-O & Complexity
  3. 08 Recursion
  4. 09 Math & Number Theory

Linear patterns

Turn O(n²) loops into O(n) scans with the patterns behind most interview questions.

  1. 10 Arrays & Strings
  2. 11 Matrices & Simulation
  3. 12 Two Pointers
  4. 13 Sliding Window
  5. 14 Hashing & Prefix Sums
  6. 15 Linked Lists
  7. 16 Stacks & Monotonic Stack
  8. 17 Queues & Deques
  9. 18 Binary Search
  10. 19 Sorting
  11. 20 String Parsing & Expression Evaluation

Trees & graphs

Think in hierarchies and networks: traversals, heaps, tries, shortest paths, dependencies.

  1. 21 Tree Traversals
  2. 22 Tree Recursion
  3. 23 Binary Search Trees
  4. 24 Heaps & Priority Queues
  5. 25 Tries
  6. 26 Graphs: BFS & DFS
  7. 27 Shortest Paths
  8. 28 Union-Find & Minimum Spanning Trees
  9. 29 Topological Sort
  10. 30 Advanced Graphs: Euler Paths, Bridges & SCCs

Paradigms

Explore choices systematically, know when greedy is safe, and build DP from recursion.

  1. 31 Backtracking
  2. 32 Greedy Algorithms
  3. 33 Intervals
  4. 34 Bit Manipulation
  5. 35 Dynamic Programming
  6. 36 DP Patterns

Expert

Design data structures on the spot and handle range-query and string-matching rounds.

  1. 37 Design Data Structures
  2. 38 Segment Trees, Fenwick & String Matching