CodeMosa

Master LeetCode Patterns

Pattern Recognition Training

Master Algorithm Patterns Through Interactive Quizzes

Build intuition for solving LeetCode problems with Duolingo-style learning. Progressive difficulty, instant feedback, and gamified progress tracking.

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39 patterns found

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Select from 50+ algorithmic patterns organized by category

Arrays & Strings

Opposite-ends, partitioning, read/write compaction

Fixed/variable windows, frequency maps, deque patterns

Intermediate10Q

Prefix sums, XOR, difference arrays, rolling prefix

Frequency maps, group-by, first/last index tracking

Intermediate10Q

Sorting + Greedy

Custom comparators, merge intervals, bucket sort

Intermediate18Q

Boundary search, rotated arrays, search on answer

Monotonic Stack

Next greater/smaller, largest rectangle, stock span

Monotonic Deque

Window max/min, shortest subarray, convex hull trick

Interval endpoints, plane sweep, timeline concurrency

Linked Lists

Fast-Slow Pointers

Cycle detection, middle node, remove Nth from end

In-place Reversal

Reverse list, reverse sublist, k-group reversal

Merge k lists, sort list, partition around value

Stacks, Queues, Heaps

Stack Simulation

Parentheses, decode/eval, two-stack queue

O(1) min stack, monotonic queue for window min/max

Intermediate12Q

Top-k, k-way merge, task scheduling, two heaps

Trees

Pre/in/post order, root-to-leaf paths, subtree DP

Level order, zigzag, right view, connect next pointers

Intermediate10Q

Validate, kth smallest, insert/delete, transform

LCA (Lowest Common Ancestor)

Binary tree LCA, BST LCA, binary lifting

Prefix search, autocomplete, bitwise trie for XOR

Graphs

Intermediate12Q

Components, islands, cycle detection, bipartite

Topological Sort

Kahn's algorithm, DFS-based, detect cycles in DAG

Dijkstra, 0-1 BFS, Bellman-Ford, multi-source

Union-Find (DSU)

Connectivity, Kruskal MST, offline queries

Kruskal's and Prim's algorithms

Kosaraju's and Tarjan's algorithms

Dynamic Programming

Intermediate12Q

Kadane, house robber, stocks, LIS

Intermediate10Q

Unique paths, min cost path, shapes

Edit distance, LCS, palindromic subsequence

Burst balloons, matrix chain, merge stones

Intermediate10Q

0/1, unbounded, bounded, multi-dimensional

TSP, assignment, DP over subsets

Count numbers with properties, tight/loose states

Advanced Patterns

Intermediate12Q

Subsets, permutations, N-Queens, Sudoku

String Algorithms

KMP, Z-algorithm, rolling hash, Manacher

Intermediate10Q

GCD/LCM, modular arithmetic, bit manipulation

Segment tree, Fenwick tree, offline tricks

Intermediate10Q

Interval scheduling, exchange argument, Huffman

LRU/LFU cache, rate limiter, randomized set

50+

Algorithm Patterns

500+

Practice Questions

10k+

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