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353 posts found
Apr 18, 2026

[Medium] 221. Maximal Square

[Medium] 221. Maximal Square
leetcodemediumarraymatrixdynamic-programming
leetcodemediummatrixdynamic-programming2d-dp
Apr 17, 2026

[Medium] 274. H-Index

[Medium] 274. H-Index
leetcodemediumarraysorting
leetcodemediumarraysortinggreedyh-index
Apr 14, 2026

[Medium] 143. Reorder List

[Medium] 143. Reorder List
leetcodemediumlinked-listtwo-pointers
leetcodemediumlinked-listfast-slow-pointersreversemerge
Mar 5, 2026

[Medium] 78. Subsets

[Medium] 78. Subsets
leetcodemediumbacktrackingdfs
leetcodemediumbacktrackingdfsrecursion
Feb 28, 2026

[Medium] 61. Rotate List

[Medium] 61. Rotate List
leetcodemediumlinked-listpython
leetcodemediumlinked-listtwo-pointers
Feb 27, 2026

[Medium] 187. Repeated DNA Sequences

[Medium] 187. Repeated DNA Sequences
leetcodemediumstringhashingsliding-windowbit-manipulation
leetcodemediumstringhashingsliding-windowbit-manipulation
Feb 17, 2026

[Hard] 42. Trapping Rain Water

[Hard] 42. Trapping Rain Water
leetcodehardtwo-pointersstackdp
leetcodehardtwo-pointersmonotonic-stackprefix-suffixdp
Feb 16, 2026

[Medium] 38. Count and Say

[Medium] 38. Count and Say
leetcodemediumstringsimulation
leetcodemediumstringsimulationrun-length-encoding
Feb 15, 2026

[Hard] 23. Merge k Sorted Lists

[Hard] 23. Merge k Sorted Lists
leetcodehardlinked-listdivide-and-conquerheap
leetcodehardlinked-listdivide-and-conquerheapmerge
Feb 9, 2026

[Medium] 91. Decode Ways

[Medium] 91. Decode Ways
leetcodemediumdynamic-programming
leetcodemediumdynamic-programmingstring
Feb 2, 2026

[Hard] 843. Guess the Word

[Hard] 843. Guess the Word
leetcodehardarraystringinteractiveminmax
leetcodehardarraystringinteractiveminmax
Feb 1, 2026

[Hard] 44. Wildcard Matching

[Hard] 44. Wildcard Matching
leetcodehardstringdynamic-programminggreedytwo-pointers
leetcodehardstringdynamic-programminggreedytwo-pointers
Jan 27, 2026

[Hard] 1136. Parallel Courses

[Hard] 1136. Parallel Courses
leetcodehardgraphtopological-sortdfsdynamic-programming
leetcodehardgraphtopological-sortdfsdynamic-programmingmemoization
Jan 26, 2026

[Medium] 209. Minimum Size Subarray Sum

[Medium] 209. Minimum Size Subarray Sum
leetcodemediumarraysliding-windowbinary-searchprefix-sum
leetcodemediumarraysliding-windowbinary-searchprefix-sumtwo-pointers
Jan 25, 2026

[Medium] 354. Russian Doll Envelopes

[Medium] 354. Russian Doll Envelopes
leetcodemediumarraydynamic-programmingbinary-searchsorting
leetcodemediumarraydynamic-programmingbinary-searchsortinglongest-increasing-subsequence
Jan 25, 2026

[Medium] 213. House Robber II

[Medium] 213. House Robber II
leetcodemediumarraydynamic-programming
leetcodemediumarraydynamic-programmingdpcircular-array
Jan 24, 2026

[Medium] 622. Design Circular Queue

[Medium] 622. Design Circular Queue
leetcodemediumarraylinked-listdesignqueue
leetcodemediumarraylinked-listdesignqueuecircular-queuedata-structure
Jan 21, 2026

[Medium] 63. Unique Paths II

[Medium] 63. Unique Paths II
leetcodemediumarraydynamic-programmingmatrix
leetcodemediumarraydynamic-programmingmatrixgridobstacles
Jan 20, 2026

Algorithm Templates: Search

Minimal, copy-paste C++ for binary search, rotated arrays, 2D search, and answer-space search. Matches Data Structures lower/upper bound style.
leetcodetemplatessearchbinary-search
leetcodetemplatessearchbinary-searchdivide-and-conquer
Jan 20, 2026

[Hard] 327. Count of Range Sum

[Hard] 327. Count of Range Sum
leetcodehardarraydivide-and-conquer
leetcodehardarraydivide-and-conquermerge-sortsegment-treeprefix-sum
Jan 19, 2026

[Easy] 645. Set Mismatch

[Easy] 645. Set Mismatch
leetcodeeasyarrayhash-tablemath
leetcodeeasyarrayhash-tablemathbit-manipulationnegative-marking
Jan 19, 2026

[Easy] 409. Longest Palindrome

[Easy] 409. Longest Palindrome
leetcodeeasystringhash-tablegreedy
leetcodeeasystringhash-tablegreedybit-manipulationpalindrome
Jan 19, 2026

[Easy] 112. Path Sum

[Easy] 112. Path Sum
leetcodeeasytreedfs
leetcodeeasytreedfsrecursionbacktracking
Jan 19, 2026

[Easy] 409. Longest Palindrome

[Easy] 409. Longest Palindrome
leetcodeeasystringhash-tablegreedy
leetcodeeasystringhash-tablegreedybit-manipulationpalindrome
Jan 18, 2026

[Hard] 732. My Calendar III

[Hard] 732. My Calendar III
leetcodehardarraybinary-searchdesignsegment-treeordered-set
leetcodehardarraybinary-searchdesignsegment-treelazy-propagationsweep-linedifference-array
Jan 17, 2026

[Medium] 729. My Calendar I

[Medium] 729. My Calendar I
leetcodemediumarraybinary-searchdesignordered-set
leetcodemediumarraybinary-searchdesignordered-setintervaloverlap-detection
Jan 17, 2026

[Hard] 315. Count of Smaller Numbers After Self

[Hard] 315. Count of Smaller Numbers After Self
leetcodehardarraybinary-searchdivide-and-conquerbinary-indexed-treesegment-treemerge-sort
leetcodehardarrayfenwick-treebinary-indexed-treecoordinate-compressioninversion-count
Jan 16, 2026

[Medium] 307. Range Sum Query - Mutable

[Medium] 307. Range Sum Query - Mutable
leetcodemediumarraysegment-treebinary-indexed-tree
leetcodemediumarraysegment-treebinary-indexed-treedata-structure
Jan 15, 2026

[Hard] 315. Count of Smaller Numbers After Self

[Hard] 315. Count of Smaller Numbers After Self
leetcodehardarraybinary-searchdivide-and-conquerbinary-indexed-treesegment-treemerge-sort
leetcodehardarrayfenwick-treebinary-indexed-treecoordinate-compressioninversion-count
Jan 14, 2026

[Medium] 310. Minimum Height Trees

[Medium] 310. Minimum Height Trees
leetcodemediumgraphtreetopological-sortbfs
leetcodemediumgraphtreetopological-sortbfspeeling-leaves
Jan 14, 2026

[Hard] 269. Alien Dictionary

[Hard] 269. Alien Dictionary
leetcodehardgraphtopological-sortstring
leetcodehardgraphtopological-sortstringbfskahn
Jan 12, 2026

[Medium] 79. Word Search

[Medium] 79. Word Search
leetcodemediumarraybacktrackingmatrixdfs
leetcodemediumarraybacktrackingmatrixdfsrecursion
Jan 12, 2026

[Hard] 51. N-Queens

[Hard] 51. N-Queens
leetcodehardarraybacktrackingrecursion
leetcodehardarraybacktrackingrecursionconstraint-satisfaction
Jan 11, 2026

[Medium] 721. Accounts Merge

[Medium] 721. Accounts Merge
leetcodemediumarrayhash-tablestringunion-finddfs
leetcodemediumarrayhash-tablestringunion-finddisjoint-setdfs
Jan 10, 2026

[Medium] 64. Minimum Path Sum

[Medium] 64. Minimum Path Sum
leetcodemediumarraydynamic-programmingmatrix
leetcodemediumarraydynamic-programmingmatrixgrid
Jan 10, 2026

[Hard] 1340. Jump Game V

[Hard] 1340. Jump Game V
leetcodehardarraydynamic-programmingdfsmemoization
leetcodehardarraydynamic-programmingdfsmemoizationrecursion
Jan 8, 2026

[Medium] 5. Longest Palindromic Substring

[Medium] 5. Longest Palindromic Substring
leetcodemediumstringtwo-pointersdynamic-programming
leetcodemediumstringtwo-pointerspalindromeexpand-around-centermanacher
Jan 5, 2026

Algorithm Templates: Heap

Minimal, copy-paste C++ for min/max heap, K-way merge, top K, and two heaps. See also Data Structures for heap patterns.
leetcodetemplatesheappriority-queue
leetcodetemplatesheappriority-queuedata-structures
Dec 14, 2025

Algorithm Templates: Greedy

Minimal, copy-paste C++ for interval scheduling, activity selection, and greedy on arrays/strings with sorting.
leetcodetemplatesgreedy
leetcodetemplatesgreedyalgorithms
Dec 11, 2025

[Easy] 67. Add Binary

[Easy] 67. Add Binary
leetcodealgorithmeasycppstringmathbit-manipulationproblem-solving
Dec 2, 2025

[Medium] 146. LRU Cache

[Medium] 146. LRU Cache
leetcodealgorithmmediumcppdesigndata-structureshash-maplinked-listproblem-solving
Dec 2, 2025

[Medium] 146. LRU Cache

[Medium] 146. LRU Cache
leetcodealgorithmmediumcppdesigndata-structureshash-maplinked-listproblem-solving
Nov 24, 2025

[Medium] 647. Palindromic Substrings

[Medium] 647. Palindromic Substrings
leetcodealgorithmmediumcppstringtwo-pointersproblem-solving
leetcodemediumstringtwo-pointerspalindromeexpand-around-center
Nov 24, 2025

[Medium] 56. Merge Intervals

[Medium] 56. Merge Intervals
leetcodealgorithmmediumcpparraysortingintervalproblem-solving
leetcodemediumarraysortingintervalsmerge
Nov 24, 2025

[Medium] 528. Random Pick with Weight

[Medium] 528. Random Pick with Weight
leetcodealgorithmmediumcppdesignbinary-searchprefix-sumproblem-solving
leetcodemediumdesignbinary-searchprefix-sumweighted-random
Nov 24, 2025

[Medium] 398. Random Pick Index

[Medium] 398. Random Pick Index
leetcodealgorithmmediumcpphash-tablereservoir-samplingproblem-solving
leetcodemediumhash-tablereservoir-samplingdesignrandomization
Nov 24, 2025

[Medium] 277. Find the Celebrity

[Medium] 277. Find the Celebrity
leetcodealgorithmmediumcppgraphtwo-pointersproblem-solving
leetcodemediumgraphtwo-pointerscelebrity
Nov 24, 2025

[Hard] 489. Robot Room Cleaner

[Hard] 489. Robot Room Cleaner
leetcodealgorithmhardcppdfsbacktrackingproblem-solving
leetcodeharddfsbacktrackingrobotsimulation
Nov 24, 2025

[Hard] 32. Longest Valid Parentheses

[Hard] 32. Longest Valid Parentheses
leetcodealgorithmhardcppstringdynamic-programmingstackproblem-solving
leetcodehardstringdynamic-programmingstacktwo-pointersgreedy
Nov 24, 2025

[Easy] 938. Range Sum of BST

[Easy] 938. Range Sum of BST
leetcodealgorithmeasycpptreebstdfsproblem-solving
leetcodeeasytreebstdfsrecursion
Nov 24, 2025

Algorithm Templates: String Processing

Minimal, copy-paste Python for sliding window, two pointers, string matching, manipulation, and parsing. See also Arrays & Strings for KMP and rolling hash.
leetcodetemplatesstring
leetcodetemplatesstringalgorithms
Nov 24, 2025

Algorithm Templates: Queue

Minimal, copy-paste Python for BFS queue, monotonic queue, priority queue, circular queue, and deque. See also Graph and Data Structures (monotonic queue).
leetcodetemplatesqueue
leetcodetemplatesqueuedata-structures
Nov 24, 2025

Algorithm Templates: Math & Bit Manipulation

Minimal, copy-paste Python for bit operations, fast exponentiation, GCD/LCM, primes, and number theory. See also Math & Geometry.
leetcodetemplatesmathbit-manipulation
leetcodetemplatesmathbit-manipulation
Nov 24, 2025

Algorithm Templates: Linked List

Minimal, copy-paste Python for traversal, two pointers, dummy node, reversal, merge, cycle detection, and circular list.
leetcodetemplateslinked-list
leetcodetemplateslinked-list
Nov 24, 2025

Algorithm Templates: DFS

Minimal, copy-paste Python for graph DFS, grid DFS, tree DFS, memoization, and iterative DFS. See also Graph and Backtracking.
leetcodetemplatesdfsgraph
leetcodetemplatesdfsgraphtraversal
Nov 24, 2025

Algorithm Templates: Data Structure Design

Minimal, copy-paste Python for LRU/LFU cache, Trie, time-based key-value store, and common design patterns.
leetcodetemplatesdesign
leetcodetemplatesdesigndata-structures
Nov 24, 2025

Algorithm Templates: BFS

Minimal, copy-paste C++ for graph and grid BFS, multi-source BFS, shortest path, and level-order traversal. See also Graph for Dijkstra and 0-1 BFS.
leetcodetemplatesbfsgraph
leetcodetemplatesbfsgraphtraversal
Nov 24, 2025

Algorithm Templates: Backtracking

Minimal, copy-paste Python for permutations, combinations, subsets, combination sum, grid pathfinding, and constraint satisfaction (N-Queens, Sudoku).
leetcodetemplatesbacktracking
leetcodetemplatesbacktrackingdfs
Nov 24, 2025

Algorithm Templates: Array & Matrix

Minimal, copy-paste C++ for two pointers, sliding window, prefix sum, binary search, and matrix operations. See also Arrays & Strings and Search.
leetcodetemplatesarraymatrix
leetcodetemplatesarraymatrix
Nov 20, 2025

[Medium] 200. Number of Islands

[Medium] 200. Number of Islands
leetcodealgorithmmediumcppdfsgraphmatrixproblem-solving
leetcodemediumdfsgraphmatrixconnected-components
Nov 18, 2025

[Medium] 969. Pancake Sorting

[Medium] 969. Pancake Sorting
leetcodealgorithmmediumcpparraysortingproblem-solving
leetcodemediumarraysortinggreedypancake-flip
Nov 18, 2025

[Medium] 49. Group Anagrams

[Medium] 49. Group Anagrams
leetcodealgorithmmediumcppstringhash-tableproblem-solving
leetcodemediumstringhash-tableanagramcounting
Nov 18, 2025

[Medium] 45. Jump Game II

[Medium] 45. Jump Game II
leetcodealgorithmmediumcpparraygreedyproblem-solving
leetcodemediumarraygreedybfsoptimization
Nov 18, 2025

[Medium] 2. Add Two Numbers

[Medium] 2. Add Two Numbers
leetcodealgorithmmediumcpplinked-listrecursionproblem-solving
leetcodemediumlinked-listrecursionmathcarry
Nov 18, 2025

[Medium] 198. House Robber

[Medium] 198. House Robber
leetcodealgorithmmediumcppdynamic-programmingdpproblem-solving
leetcodemediumdynamic-programmingdparrayoptimization
Nov 18, 2025

[Easy] 509. Fibonacci Number

[Easy] 509. Fibonacci Number
leetcodealgorithmeasycppdynamic-programmingrecursionproblem-solving
leetcodeeasydynamic-programmingrecursionmathfibonacci
Nov 15, 2025

[Medium] 146. LRU Cache

[Medium] 146. LRU Cache
leetcodealgorithmmediumcppdesigndata-structureshash-maplinked-listproblem-solving
Nov 14, 2025

[Hard] 460. LFU Cache

[Hard] 460. LFU Cache
leetcodealgorithmhardcppdesigndata-structureshash-maplinked-listproblem-solving
Nov 14, 2025

Algorithm Templates: Stack

Minimal, copy-paste C++ for parentheses matching, expression evaluation, nested structures, and monotonic stack.
leetcodetemplatesstackdata-structures
leetcodetemplatesstackdata-structures
Nov 14, 2025

Algorithm Templates: Calculator

Minimal, copy-paste C++ for expression evaluation with +, −, ×, ÷ and parentheses. See also Stack for RPN and nested expressions.
leetcodetemplatescalculatorexpression-evaluation
leetcodetemplatescalculatorexpression-evaluationstack
Nov 14, 2025

[Medium] 224. Basic Calculator

[Medium] 224. Basic Calculator
leetcodealgorithmmediumcppstringstackexpression-evaluationproblem-solving
leetcodemediumstringstackcalculatorexpression-evaluationparentheses
Nov 14, 2025

[Hard] 772. Basic Calculator III

[Hard] 772. Basic Calculator III
leetcodealgorithmhardcppstringstackrecursionexpression-evaluationproblem-solving
leetcodehardstringstackcalculatorrecursionexpression-evaluationparentheses
Nov 14, 2025

[Medium] 227. Basic Calculator II

[Medium] 227. Basic Calculator II
leetcodealgorithmmediumcppstringstackexpression-evaluationproblem-solving
leetcodemediumstringstackcalculatorexpression-evaluation
Nov 5, 2025

[Medium] 324. Wiggle Sort II

[Medium] 324. Wiggle Sort II
leetcodealgorithmmediumcpparraysnth-elementthree-way-partitionindex-mappingproblem-solving
leetcodemediumarraywigglenth_elementpartition
Nov 5, 2025

[Easy] 20. Valid Parentheses

[Easy] 20. Valid Parentheses
leetcodealgorithmeasycppstringstackproblem-solving
leetcodeeasystringstackparenthesesvalidation
Nov 5, 2025

[Medium] 525. Contiguous Array

[Medium] 525. Contiguous Array
leetcodealgorithmmediumcpparrayshash-mapprefix-sumproblem-solving
leetcodemediumarrayhash-mapprefix-sumsubarray
Nov 5, 2025

[Hard] 480. Sliding Window Median

[Hard] 480. Sliding Window Median
leetcodealgorithmhardcpparraysmultisetsliding-windowtwo-heapsproblem-solving
leetcodehardarraymultisetsliding-windowtwo-heapsmedian
Nov 5, 2025

[Hard] 239. Sliding Window Maximum

[Hard] 239. Sliding Window Maximum
leetcodealgorithmhardcpparraysdequesliding-windowmonotonic-queueproblem-solving
leetcodehardarraydequesliding-windowmonotonic-queue
Nov 5, 2025

[Easy] 485. Max Consecutive Ones

[Easy] 485. Max Consecutive Ones
leetcodealgorithmeasycpparrayssliding-windowproblem-solving
leetcodeeasyarraysliding-windowcounting
Nov 5, 2025

[Medium] 18. 4Sum

[Medium] 18. 4Sum
leetcodealgorithmmediumcpparraystwo-pointerssortingproblem-solving
Oct 6, 2025

[Medium] 912. Sort an Array

[Medium] 912. Sort an Array
pythonsortingmerge-sortheap-sortcounting-sortdata-structuresdivide-conquerproblem-solving
Sep 24, 2025

Meta‑Style LeetCode Question List

Meta‑Style LeetCode Question List
leetcodealgorithmmetainterview-preparationpractice-listfaangcoding-interviewproblem-solvingcompetitive-programmingdata-structures
Sep 24, 2025

Hash Table Mastery List

🧩 Hash Table Mastery List
leetcodealgorithmhashdata-structuresinterview-preparationpractice-listhash-tablehash-mapproblem-solvingcompetitive-programming
Sep 24, 2025

LeetCode Linked List Mastery List

LeetCode Linked List Mastery List
leetcodealgorithmlinked-listdata-structuresinterview-preparationpractice-listproblem-solvingcompetitive-programmingpointerstraversal
Sep 23, 2025

Python Quick Reference for LeetCode

📚 Python Quick Reference for LeetCode
pythondata-structuresreferencecheat-sheetprogrammingcontainersalgorithmscompetitive-programming
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