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.

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43problems
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.

Arrays Strings Linked List Trees Graphs DP Recursion Sorting Searching Hashing Stack Queue

All Easy Medium Hard

#	Title	Acceptance	Difficulty
1	Find the Missing Term in a Geometric Progression Introduction · Data Structures Basics · Array	88.72%	Basic
2	Find the Missing Term in an Arithmetic Progression Introduction · Data Structures Basics · Array	82.87%	Basic
3	Find GCD of Multiple Numbers Data Structures Basics · Array · Basics	98.77%	Basic
4	Find LCM of Multiple Numbers Data Structures Basics · Array · Basics	87.89%	Basic
5	Find the Longest Consecutive Sequence of the Same Digit Data Structures Basics · Array · String	84.75%	Basic
6	Remove All Occurrences of a Digit Data Structures Basics · Array · String	78.62%	Basic
7	Find the Second Smallest of Four Numbers Data Structures Basics · Array · Sorting Algorithms	89.85%	Basic
8	Find the Second Largest of Four Numbers Data Structures Basics · Array · Searching Algorithms	89.48%	Basic
9	Permutation of an Array Array · Recursion	68.00%	Medium
10	Missing And Repeating Array	24.83%	Easy
11	Search In Rotated Sorted Array Array · Searching Algorithms	37.64%	Medium
12	Longest Common Prefix Array · String	44.20%	Easy
13	Count Inversions Array · Sorting Algorithms	16.93%	Medium
14	2Sum - Pair With Given Sum Array · Hashing · Hashmap	30.61%	Easy
15	Maximize Number of 1's Array · Binary Search	50.00%	Medium
16	Maximum fruit gathering by birds Array	50.00%	Easy
17	Sum of elements of smallest subarray greater than x Array	50.00%	Easy
18	Minimum sum Array · Sorting Algorithms	17.14%	Medium
19	Number of Pairs Array	21.82%	Medium
20	Find Transition Point Array · Searching Algorithms	37.90%	Easy
21	0-1 Knapsack Problem Array · Dynamic Programming	50.00%	Medium
22	Rod Cutting Array · Dynamic Programming	50.00%	Medium
23	Stock buy and sell Array · Dynamic Programming	29.18%	Medium
24	Maximum Meetings in One Room Array · Sorting Algorithms	33.57%	Medium
25	Distinct Paths II Array · Recursion · Dynamic Programming	50.00%	Medium
26	Minimum Path Sum Array · Dynamic Programming · 2D Array	50.00%	Medium
27	Distinct Paths Array · Recursion · Dynamic Programming	50.00%	Medium
28	Longest Increasing Subsequence Array · Dynamic Programming	20.00%	Medium
29	Longest Common Subsequence Array · String · Dynamic Programming	50.00%	Medium
30	Cake Distribution Problem Array · Searching Algorithms	64.62%	Hard
31	Search Insert Position Array · Sorting Algorithms	48.03%	Easy
32	3 Sum Array · Sorting Algorithm	35.80%	Medium
33	Making A Large Island Graph · BFS · DFS	52.36%	Hard
34	Stepping Numbers BFS · DFS	48.44%	Medium
35	Course Schedule Graph · BFS · DFS	51.77%	Medium
36	You and your books Array · Dynamic Programming	50.00%	Easy
37	Next Smallest Palindrome Array	19.63%	Hard
38	Count Smaller elements Array	38.16%	Hard
39	Find Kth Rotation Array · Stack · Searching Algorithm	23.16%	Easy
40	Merge Sorted Arrays Array · Sorting Algorithms	32.01%	Easy
41	Missing In Array Array · Searching Algorithms	29.59%	Easy
42	Maximum Product Of Two Numbers Array · Sorting Algorithms	81.34%	Basic
43	Maximum Subarray Sum Array	36.28%	Medium

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.