Practice
Coding interview problems organized by topic. Every problem ships with a problem statement, constraints, worked examples, progressive hints, a solution-approach outline, and complexity analysis — written for candidates who want to pattern-match, not memorize.
By Sam K., Founder of InterviewChamp.AI
501 problems · 15 topics · 119 companies · last updated
Today's problem ·
189. Rotate Array
mediumRotate an array right by k steps, in-place, with O(1) extra space. The elegant solve uses three reversals — a trick that surprises candidates the first time they see it.
Solve nowCurated paths
Opinionated starting points — pick one and don't think about it.
Junior Warmup 10
Hit the floor of every coding-interview rubric: recognize the canonical patterns, narrate trade-offs, and finish a problem in under twenty minutes.
10 problems · ~8hStart pathBinary Search Drill 12-Day
Write the lo/hi/mid template eyes-closed, recognize 'binary search on the answer' problems by their shape, and explain why your loop terminates.
12 problems · ~14hStart pathTree Traversal Drill 12-Day
Reach for the right traversal — preorder, inorder, postorder, or BFS — within seconds of reading a tree problem, and write the base case before the recursive case.
12 problems · ~14hStart pathGraph Mastery 14-Day
Spot DFS vs BFS vs union-find vs Dijkstra at the problem statement, narrate the choice, and ship the solution without rebuilding the templates from scratch.
14 problems · ~22hStart pathDP Foundations 21-Day
Name the recurrence before you write code, recognize 1D vs 2D state, and ship a memoized solution inside the interview clock.
21 problems · ~32hStart pathFAANG 30-Day
Pattern-match the 80% of FAANG questions that come from 20% of the canon.
30 problems · ~45hStart pathPatterns-First 50
Stop solving each problem from scratch. Recognize the pattern in the first thirty seconds and execute the template.
50 problems · ~60hStart path
Browse by topic
All 15 topics · sorted by problem count.
Math
60 problems
31 easy · 26 medium · 3 hard
DP 1D
51 problems
4 easy · 33 medium · 14 hard
2D Dynamic Programming
50 problems
0 easy · 25 medium · 25 hard
Recursion
50 problems
5 easy · 29 medium · 16 hard
Bit Manipulation
40 problems
20 easy · 19 medium · 1 hard
Arrays
25 problems
9 easy · 13 medium · 3 hard
Binary Search
25 problems
5 easy · 16 medium · 4 hard
Dynamic Programming
25 problems
4 easy · 18 medium · 3 hard
Graphs
25 problems
2 easy · 19 medium · 4 hard
Hash Tables
25 problems
13 easy · 11 medium · 1 hard
Heaps
25 problems
4 easy · 15 medium · 6 hard
Linked Lists
25 problems
8 easy · 13 medium · 4 hard
Stacks
25 problems
6 easy · 16 medium · 3 hard
Strings
25 problems
11 easy · 12 medium · 2 hard
Trees
25 problems
10 easy · 13 medium · 2 hard
Browse by company
Drill what each company actually asks. Sourced from public Glassdoor + Blind + Levels.fyi posts.
Browse by pattern
The mental templates that crack most coding interviews.
Recently added
Fresh problems verified this week.
- mediumMax Consecutive Ones IIIArraysVerified
- hardMaximum GapArraysVerified
- easyRichest Customer WealthArraysVerified
- easyRunning Sum of 1d ArrayArraysVerified
- easySquares of a Sorted ArrayArraysVerified
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