DSA Interview Preparation
100 curated problems across 10 topics, tagged with the companies that ask them. Follow the 4-week strategy below, or jump straight into filtered practice.
100
Curated problems
10
Topics
10
Companies covered
26 / 63 / 11
Easy / Medium / Hard
How it works
Pick your target
Filter by company, topic, and difficulty. See exactly what gets asked where.
Solve in the browser
Every problem opens with a runnable Java workspace. Code, run, and test instantly.
Learn from the solution
Stuck? Reveal the approach, complexity analysis, and a clean Java solution.
The 4-week strategy
One theme per week. Solve every problem in the compiler before revealing the solution — struggle is where the learning happens.
Foundations: Arrays & Strings
Interviewers warm up with arrays and strings because they expose how you think about indices, hashing, and edge cases. Master two-pointer and sliding-window intuition here.
Practice this phaseLinear Structures: Lists, Stacks & Queues
Pointer manipulation and LIFO/FIFO discipline. These problems test implementation accuracy under pressure — exactly what onsite rounds probe.
Practice this phaseSearch & Hierarchies: Binary Search, Trees & Heaps
O(log n) thinking and recursion over hierarchies. Trees and heaps dominate mid-level rounds at product companies.
Practice this phaseThe Deep End: Graphs & Dynamic Programming
Traversal, topological order, and state-based optimization. These separate prepared candidates from exceptional ones — pace yourself and revisit.
Practice this phaseTopics
Arrays
Contiguous memory, indexing, in-place tricks — the foundation of every interview round.
Strings
Character counting, sliding windows over text, and palindrome thinking.
Linked Lists
Pointer manipulation, fast/slow pointers, and re-wiring nodes without extra memory.
Stacks
LIFO thinking — matching, monotonic stacks, and undo-style state management.
Queues
FIFO processing, BFS foundations, and sliding windows over streams.
Binary Search
O(log n) search space reduction — on arrays and on the answer itself.
Trees
Recursion over hierarchies — DFS, BFS, BST properties, and serialization.
Heaps
Priority queues for top-K, merging, and streaming medians.
Graphs
Traversal, connected components, topological order, and shortest paths.
Dynamic Programming
Overlapping subproblems + optimal substructure — memoize, then tabulate.
Practice by company
Tags are based on commonly reported interview questions. Focus on your target company in the final weeks before the loop.
Your DSA progress
Practice nowNo problems attempted yet. Start with arrays — the foundation of every interview round.
Consistency beats intensity
Two problems daily for four weeks prepares you better than 40 problems the weekend before. Your progress is saved locally — pick up where you left off.
Start today