LeetCode Templates
LeetCode Templates
Master index and category collections of solution patterns and Meta practice lists
Array & Matrix
Subcategories: Two Pointers, Sliding Window (fixed/variable), Prefix Sum / Difference Array, Binary Search (sorted/rotated), Matrix Operations (rotate, spiral), Array Manipulation (merge intervals, jump game)
String Processing
Subcategories: Sliding Window (longest substring, minimum window), Two Pointers (palindrome, reverse), String Matching (KMP), String Manipulation (anagrams, duplicates), Parsing (decode string, abbreviations)
Linked List
Subcategories: Basic Operations (traversal, insertion, deletion), Two Pointers (fast/slow, kth from end), Dummy Node Pattern, Reversal (entire list, between positions, k-group), Merge (two sorted, k sorted), Cycle Detection, Circular Linked List
Tree
Subcategories: Tree Traversals (iterative inorder/level-order), LCA (Binary Lifting), HLD (Heavy-Light Decomposition) skeleton, BST operations, Tree DFS patterns
BFS
Subcategories: Basic BFS (graph traversal), BFS on Grid (4/8-directional), Multi-source BFS, BFS for Shortest Path (unweighted), Level-order Traversal (tree), BFS with State
DFS
Subcategories: Basic DFS (graph traversal), DFS on Grid (connected components, paths), DFS on Tree (preorder, inorder, postorder), DFS with Memoization, Iterative DFS (using stack)
Dynamic Programming
Subcategories: 1D DP (Knapsack/linear transitions), 2D DP (grid paths/obstacles), Digit DP (count numbers with property), Bitmask DP (TSP/subsets), LIS (Patience Sorting)
Backtracking
Subcategories: Permutations (with/without duplicates), Combinations (choose k from n), Subsets (power set generation), Combination Sum (unbounded/reuse elements), Grid Backtracking (Word Search, path finding), Constraint Satisfaction (N-Queens, Sudoku), Palindrome Partitioning
Greedy
Subcategories: Interval Scheduling, Activity Selection, Greedy on Arrays (Kadane's, stock problems), Greedy on Strings (subsequence matching), Greedy with Sorting (assign cookies, queue reconstruction), Jump Problems, Scheduling Problems
Stack
Subcategories: Stack (expression evaluation, parentheses matching), Monotonic Stack, Calculator (basic, II, III), Reverse Polish Notation, Nested Structure Processing
Queue
Subcategories: Basic Queue Operations, BFS with Queue, Monotonic Queue (sliding window max), Priority Queue (heap, k-way merge, top k), Circular Queue, Double-ended Queue (Deque)
Heap
Subcategories: Min Heap, Max Heap, Custom Comparators (struct, lambda), K-way Merge, Top K Elements, Two Heaps (median finding), Dijkstra's Algorithm, Frequency-Based Problems, Scheduling Problems
Graph
Subcategories: BFS / Shortest Path (unweighted), Multi-source BFS (grids/graphs), BFS on Bitmask State (visit all keys), Topological Sort (Kahn / DFS), Dijkstra (nonnegative weights), 0-1 BFS (edge weights 0 or 1), Disjoint Set Union (DSU), Tarjan SCC (strongly connected components), Bridges & Articulation Points
Data Structure Design
Subcategories: LRU Cache, LFU Cache, Trie (Prefix Tree), Time-based Key-Value Store, Design Patterns (Random Pick with Weight, Tic-Tac-Toe)
Advanced Algorithms
Subcategories: Coordinate Compression, Meet-in-the-Middle (subset sums), Manacher (longest palindromic substring O(n)), Z-Algorithm (pattern occurrences), Bitwise Trie (max XOR pair), Sweep Line (intervals)
Math & Bit Manipulation
Subcategories: Bit Operations (set, clear, toggle, count), Common Bit Tricks (lowest set bit, power of 2), Single Number problems, Gray Code, Fast Exponentiation, GCD and LCM, Prime Numbers (Sieve of Eratosthenes), Number Theory
Search
Subcategories: Binary Search (sorted array, rotated array, answer space), Search in 2D Matrix, Advanced Search (merge sort on prefix sums, divide and conquer), Search Templates and Patterns