Pattern Recognition

100 drills to train your problem-solving instinct. See a problem, identify the method — before writing any code.

Random Pattern

Two Pointers

15 drills

Easy Medium Hard

Dynamic Programming

14 drills

Medium Easy

Sliding Window

6 drills

Easy Medium Hard

Prefix Sum

3 drills

Easy Medium

Pointer Walk

2 drills

Easy

Stack

8 drills

Medium Easy

Monotonic Stack

2 drills

Medium

Hash Map

8 drills

Easy Medium

Sorting

2 drills

Easy

Divide & Conquer

4 drills

Medium

Three Pointers

1 drills

Medium

Tree Recursion

12 drills

Easy Medium

Queue / BFS

6 drills

Medium

DFS / Recursion

9 drills

Easy Medium

Backtracking

9 drills

Medium

Binary Search

6 drills

Easy Medium

Heap / Priority Queue

10 drills

Easy Medium Hard

Greedy

11 drills

Easy Medium

Bit Manipulation

6 drills

Easy Medium

Topological Sort

3 drills

Medium

Monotonic Deque

1 drills

Hard

Trie

4 drills

Medium Hard

Interval Merge

2 drills

Medium

Matrix Traversal

3 drills

Medium

Math / Number Theory

1 drills

Medium

Knapsack DP

2 drills

Medium