Think in patterns.
Solve like it’s the interview.
hand-picked DSA problems in C#, Java, Python, C++ and JavaScript. Run your code, climb the leaderboard and keep your streak alive.
- 63problems
- 12core patterns
- 5languages
- 2 Lakh+learners trained
Bubble sort
ArraysO(n²)Running
Compare neighbours, swap when out of order.
Inorder traversal
TreesDFSO(n)
Visit order:
Breadth-first search
GraphsQueueO(V+E)
Level order:
Longest common subsequence
Dynamic ProgrammingO(mn)
dp[i][j] = best length for the first i and j characters.
Browse by pattern
Master the idea once, solve the whole family.
| # | Title | Acceptance | Difficulty |
|---|---|---|---|
| 1 | Calculate a^b Using Exponentiation by Squaring Data Structures Basics · Searching Algorithms · Sorting Algorithms | 86.53% | Basic |
| 2 | Find the Nth Fibonacci Number Efficiently Data Structures Basics · Recursion · Dynamic Programming | 85.25% | Basic |
| 3 | Flood Fill Recursion | 69.00% | Medium |
| 4 | Number of Islands Recursion | 66.00% | Medium |
| 5 | Remove Consecutive Duplicates Recursion | 60.00% | Easy |
| 6 | Binary Tree Post Order Traversal Tree · Recursion · Traversal | 79.59% | Easy |
| 7 | Binary Tree Zigzag Level Order Traversal Tree · Recursion · Traversal | 71.48% | Medium |
| 8 | Binary Tree Level Order Traversal Tree · Recursion · Traversal | 79.68% | Easy |
| 9 | Binary Tree Inorder Traversal Recursion · Trees · Traversal | 75.68% | Easy |
| 10 | Binary Tree Preorder Traversal Tree · Recursion · Binary Tree | 79.85% | Easy |
| 11 | Search in a 2D Matrix Recursion · Binary Search | 86.00% | Medium |
| 12 | Find Minimum In Rotated Sorted Array Recursion | 89.00% | Medium |
| 13 | Peak Element In Rotated Array Recursion | 88.00% | Easy |
| 14 | Generate All Subsequence Recursion | 56.00% | Medium |
| 15 | Check if Binary Tree is Balanced Recursion | 77.00% | Medium |
| 16 | Generate All Subsets Recursion | 60.00% | Medium |
| 17 | Count Nodes in Binary Tree Recursion | 64.00% | Medium |
| 18 | Letter Combinations of Phone Number Recursion | 60.00% | Medium |
| 19 | Tiling Problem Recursion | 50.00% | Medium |
| 20 | Permutation Without Duplicates Recursion | 67.00% | Medium |
| 21 | Combination Sum II Recursion | 76.00% | Medium |
| 22 | Target Sum Ways Recursion | 64.00% | Hard |
| 23 | Partition Equal Subset Recursion | 77.00% | Easy |
| 24 | Unique Path Recursion | 56.00% | Hard |
| 25 | Rat In A Maze Recursion | 38.00% | Hard |
| 26 | Permutation of an Array Array · Recursion | 68.00% | Medium |
| 27 | Permutation of A String String · Recursion | 66.00% | Medium |
| 28 | Subsets with Duplicates Recursion | 74.00% | Medium |
| 29 | Factorial of N Recursion | 60.00% | Easy |
| 30 | Count Ways To Reach Nth Stair Recursion | 60.00% | Medium |
| 31 | Friends Pairing Problem Recursion | 50.00% | Medium |
| 32 | Count Binary Strings Recursion | 60.00% | Medium |
| 33 | Fibonacci Series (Tree Recursion) Recursion | 60.00% | Medium |
| 34 | Check String Is Subsequence To Another Recursion | 75.00% | Medium |
| 35 | Convert String to Integer Recursion | 60.00% | Medium |
| 36 | Replace pi to 3.14 Recursion | 75.00% | Easy |
| 37 | Remove All Occurrence of A Character Recursion | 75.00% | Easy |
| 38 | Count Characters Recursion | 85.00% | Easy |
| 39 | Check Palindrome Recursion | 90.00% | Easy |
| 40 | Reverse A String Recursion | 48.00% | Easy |
| 41 | Product of All Array Elements Recursion | 80.00% | Easy |
| 42 | Sum of Array Elements Recursion | 58.00% | Easy |
| 43 | Reverse An Array Recursion | 85.00% | Easy |
| 44 | All Occurrence Of An Element Recursion | 59.00% | Easy |
| 45 | Last Occurrence Of An Element Recursion | 65.00% | Easy |
| 46 | First Occurrence Of An Element In An Array Recursion | 75.00% | Easy |
| 47 | Check Array is Sorted Recursion | 80.00% | Basic |
| 48 | Find Maximum / Minimum in Array Recursion | 75.00% | Easy |
| 49 | Print Array Elements Recursion | 50.00% | Easy |
| 50 | Fibonacci Series Recursion | 85.00% | Easy |
Practice that builds the habit
Three steps, repeated every day.
- 1
Pick a pattern
Start from an idea such as two pointers or BFS, then move through easy, medium and hard.
- 2
Code and run
Write in your language, run on sample cases and submit against every hidden test.
- 3
Climb the board
Every solve earns points. Keep a daily streak and see where you stand this month.
Want a plan, not just problems?
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