🧠 My LeetCode Solutions

Welcome to my LeetCode solutions repository!

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🎯 Statistics

Total Questions: 432

Difficulty Distribution

Difficulty	Count
Easy	243
Medium	171
Hard	18

Topics Overview

Topic	Number of Questions
Array	227
Backtracking	14
Binary Search	46
Binary Search Tree	9
Binary Tree	33
Bit Manipulation	22
Brainteaser	3
Breadth-First Search	32
Bucket Sort	3
Combinatorics	1
Counting	25
Counting Sort	2
Data Stream	5
Database	13
Depth-First Search	42
Design	19
Divide and Conquer	14
Doubly-Linked List	2
Dynamic Programming	19
Enumeration	6
Game Theory	2
Geometry	1
Graph	5
Greedy	23
Hash Function	4
Hash Table	96
Heap (Priority Queue)	16
Interactive	2
Line Sweep	1
Linked List	27
Math	80
Matrix	30
Memoization	3
Merge Sort	3
Monotonic Queue	1
Monotonic Stack	12
Number Theory	6
Ordered Set	1
Prefix Sum	30
Queue	7
Quickselect	2
Radix Sort	2
Recursion	15
Rolling Hash	1
Shortest Path	2
Simulation	32
Sliding Window	36
Sorting	52
Stack	35
String	89
String Matching	5
Tree	36
Trie	3
Two Pointers	60
Union Find	6

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Array (Total: 227)

• 506. Relative Ranks
  Difficulty: Easy

• 1. Two Sum
  Difficulty: Easy

• 1018. Largest Perimeter Triangle
  Difficulty: Easy

• 1019. Squares of a Sorted Array
  Difficulty: Easy

• 1028. Interval List Intersections
  Difficulty: Medium

• 1034. Subarrays with K Different Integers
  Difficulty: Hard

• 1036. Rotting Oranges
  Difficulty: Medium

• 1044. Find Common Characters
  Difficulty: Easy

• 1046. Max Consecutive Ones III
  Difficulty: Medium

• 105. Construct Binary Tree from Preorder and Inorder Traversal
  Difficulty: Medium

• 1056. Capacity To Ship Packages Within D Days
  Difficulty: Medium

• 1072. Next Greater Node In Linked List
  Difficulty: Medium

• 108. Convert Sorted Array to Binary Search Tree
  Difficulty: Easy

• 11. Container With Most Water
  Difficulty: Medium

• 1127. Last Stone Weight
  Difficulty: Easy

• 118. Pascal's Triangle
  Difficulty: Easy

• 119. Pascal's Triangle II
  Difficulty: Easy

• 121. Best Time to Buy and Sell Stock
  Difficulty: Easy

• 1210. Mean of Array After Removing Some Elements
  Difficulty: Easy

• 1227. Number of Equivalent Domino Pairs
  Difficulty: Easy

• 1242. Matrix Block Sum
  Difficulty: Medium

• 128. Longest Consecutive Sequence
  Difficulty: Medium

• 130. Surrounded Regions
  Difficulty: Medium

• 1329. Minimum Cost to Move Chips to The Same Position
  Difficulty: Easy

• 1349. Check If It Is a Straight Line
  Difficulty: Easy

• 1353. Find Resultant Array After Removing Anagrams
  Difficulty: Easy

• 1354. Find Players With Zero or One Losses
  Difficulty: Medium

• 136. Single Number
  Difficulty: Easy

• 1370. Count Number of Nice Subarrays
  Difficulty: Medium

• 1380. Number of Closed Islands
  Difficulty: Medium

• 1392. Find the Difference of Two Arrays
  Difficulty: Easy

• 14. Longest Common Prefix
  Difficulty: Easy

• 1408. Find the Smallest Divisor Given a Threshold
  Difficulty: Medium

• 1414. Shortest Path in a Grid with Obstacles Elimination
  Difficulty: Hard

• 1468. Check If N and Its Double Exist
  Difficulty: Easy

• 1477. Product of the Last K Numbers
  Difficulty: Medium

• 1497. Design a Stack With Increment Operation
  Difficulty: Medium

• 15. 3Sum
  Difficulty: Medium

• 150. Evaluate Reverse Polish Notation
  Difficulty: Medium

• 1510. Find Lucky Integer in an Array
  Difficulty: Easy

• 153. Find Minimum in Rotated Sorted Array
  Difficulty: Medium

• 154. Find Minimum in Rotated Sorted Array II
  Difficulty: Hard

• 1582. Design Browser History
  Difficulty: Medium

• 1586. Longest Subarray of 1's After Deleting One Element
  Difficulty: Medium

• 16. 3Sum Closest
  Difficulty: Medium

• 1603. Running Sum of 1d Array
  Difficulty: Easy

• 1605. Minimum Number of Days to Make m Bouquets
  Difficulty: Medium

• 1615. Range Sum of Sorted Subarray Sums
  Difficulty: Medium

• 162. Find Peak Element
  Difficulty: Medium

• 164. Maximum Gap
  Difficulty: Medium

• 1646. Kth Missing Positive Number
  Difficulty: Easy

• 1656. Count Good Triplets
  Difficulty: Easy

• 167. Two Sum II - Input Array Is Sorted
  Difficulty: Medium

• 1675. Magnetic Force Between Two Balls
  Difficulty: Medium

• 1677. Matrix Diagonal Sum
  Difficulty: Easy

• 1682. Most Visited Sector in a Circular Track
  Difficulty: Easy

• 169. Majority Element
  Difficulty: Easy

• 1720. Crawler Log Folder
  Difficulty: Easy

• 1741. Sort Array by Increasing Frequency
  Difficulty: Easy

• 1755. Defuse the Bomb
  Difficulty: Easy

• 1776. Minimum Operations to Reduce X to Zero
  Difficulty: Medium

• 1781. Check If Two String Arrays are Equivalent
  Difficulty: Easy

• 1787. Sum of Absolute Differences in a Sorted Array
  Difficulty: Medium

• 1791. Richest Customer Wealth
  Difficulty: Easy

• 18. 4Sum
  Difficulty: Medium

• 1848. Sum of Unique Elements
  Difficulty: Easy

• 1876. Map of Highest Peak
  Difficulty: Medium

• 1878. Check if Array Is Sorted and Rotated
  Difficulty: Easy

• 189. Rotate Array
  Difficulty: Medium

• 1918. Maximum Score of a Good Subarray
  Difficulty: Hard

• 1951. Find the Winner of the Circular Game
  Difficulty: Medium

• 198. House Robber
  Difficulty: Medium

• 1993. Sum of All Subset XOR Totals
  Difficulty: Easy

• 200. Number of Islands
  Difficulty: Medium

• 2000. Minimum Speed to Arrive on Time
  Difficulty: Medium

• 204. Count Primes
  Difficulty: Medium

• 2047. Find a Peak Element II
  Difficulty: Medium

• 209. Minimum Size Subarray Sum
  Difficulty: Medium

• 2103. Find All Groups of Farmland
  Difficulty: Medium

• 2106. Find Greatest Common Divisor of Array
  Difficulty: Easy

• 2137. Final Value of Variable After Performing Operations
  Difficulty: Easy

• 2144. Maximum Difference Between Increasing Elements
  Difficulty: Easy

• 215. Kth Largest Element in an Array
  Difficulty: Medium

• 216. Combination Sum III
  Difficulty: Medium

• 217. Contains Duplicate
  Difficulty: Easy

• 219. Contains Duplicate II
  Difficulty: Easy

• 2211. K Radius Subarray Averages
  Difficulty: Medium

• 2245. Destroying Asteroids
  Difficulty: Medium

• 2249. Count the Hidden Sequences
  Difficulty: Medium

• 2261. All Divisions With the Highest Score of a Binary Array
  Difficulty: Medium

• 2265. Partition Array According to Given Pivot
  Difficulty: Medium

• 2277. Count Equal and Divisible Pairs in an Array
  Difficulty: Easy

• 228. Summary Ranges
  Difficulty: Easy

• 229. Majority Element II
  Difficulty: Medium

• 2294. Minimum Time to Complete Trips
  Difficulty: Medium

• 2308. Divide Array Into Equal Pairs
  Difficulty: Easy

• 2320. Find All K-Distant Indices in an Array
  Difficulty: Easy

• 2331. Intersection of Multiple Arrays
  Difficulty: Easy

• 2342. Minimum Average Difference
  Difficulty: Medium

• 2350. Find Closest Number to Zero
  Difficulty: Easy

• 2358. Number of Ways to Split Array
  Difficulty: Medium

• 2375. Minimum Obstacle Removal to Reach Corner
  Difficulty: Hard

• 238. Product of Array Except Self
  Difficulty: Medium

• 2394. Count Subarrays With Score Less Than K
  Difficulty: Hard

• 240. Search a 2D Matrix II
  Difficulty: Medium

• 2429. Design a Food Rating System
  Difficulty: Medium

• 2436. Make Array Zero by Subtracting Equal Amounts
  Difficulty: Easy

• 2465. Shifting Letters II
  Difficulty: Medium

• 2478. Longest Nice Subarray
  Difficulty: Medium

• 2486. Most Frequent Even Element
  Difficulty: Easy

• 2527. Count Subarrays With Fixed Bounds
  Difficulty: Hard

• 2530. Minimize Maximum of Array
  Difficulty: Medium

• 2546. Number of Subarrays With GCD Equal to K
  Difficulty: Medium

• 2551. Apply Operations to an Array
  Difficulty: Easy

• 2552. Maximum Sum of Distinct Subarrays With Length K
  Difficulty: Medium

• 2557. Number of Subarrays With LCM Equal to K
  Difficulty: Medium

• 2581. Divide Players Into Teams of Equal Skill
  Difficulty: Medium

• 26. Remove Duplicates from Sorted Array
  Difficulty: Easy

• 2609. Distinct Prime Factors of Product of Array
  Difficulty: Medium

• 2614. Maximum Count of Positive Integer and Negative Integer
  Difficulty: Easy

• 2626. Count the Number of Good Subarrays
  Difficulty: Medium

• 2634. Minimum Common Value
  Difficulty: Easy

• 268. Missing Number
  Difficulty: Easy

• 27. Remove Element
  Difficulty: Easy

• 2714. Left and Right Sum Differences
  Difficulty: Easy

• 2721. Sum of Distances
  Difficulty: Medium

• 2751. Sliding Subarray Beauty
  Difficulty: Medium

• 2791. Find the Losers of the Circular Game
  Difficulty: Easy

• 283. Move Zeroes
  Difficulty: Easy

• 2836. Neither Minimum nor Maximum
  Difficulty: Easy

• 2876. Number of Employees Who Met the Target
  Difficulty: Easy

• 303. Range Sum Query - Immutable
  Difficulty: Easy

• 304. Range Sum Query 2D - Immutable
  Difficulty: Medium

• 31. Next Permutation
  Difficulty: Medium

• 3154. Maximum Value of an Ordered Triplet I
  Difficulty: Easy

• 3213. Count Subarrays Where Max Element Appears at Least K Times
  Difficulty: Medium

• 3234. Double Modular Exponentiation
  Difficulty: Medium

• 3236. Smallest Missing Integer Greater Than Sequential Prefix Sum
  Difficulty: Easy

• 33. Search in Rotated Sorted Array
  Difficulty: Medium

• 3321. Type of Triangle
  Difficulty: Easy

• 3367. Find the Sum of Encrypted Integers
  Difficulty: Easy

• 3381. Shortest Subarray With OR at Least K I
  Difficulty: Easy

• 34. Find First and Last Position of Element in Sorted Array
  Difficulty: Medium

• 347. Top K Frequent Elements
  Difficulty: Medium

• 349. Intersection of Two Arrays
  Difficulty: Easy

• 35. Search Insert Position
  Difficulty: Easy

• 350. Intersection of Two Arrays II
  Difficulty: Easy

• 3533. Snake in Matrix
  Difficulty: Easy

• 3558. Find a Safe Walk Through a Grid
  Difficulty: Medium

• 3581. The Two Sneaky Numbers of Digitville
  Difficulty: Easy

• 36. Valid Sudoku
  Difficulty: Medium

• 3644. Minimum Positive Sum Subarray
  Difficulty: Easy

• 3656. Minimum Number of Operations to Make Elements in Array Distinct
  Difficulty: Easy

• 3747. Maximum Difference Between Adjacent Elements in a Circular Array
  Difficulty: Easy

• 3778. Transform Array by Parity
  Difficulty: Easy

• 3849. Equal Sum Grid Partition I
  Difficulty: Medium

• 39. Combination Sum
  Difficulty: Medium

• 3973. Flip Square Submatrix Vertically
  Difficulty: Easy

• 4. Median of Two Sorted Arrays
  Difficulty: Hard

• 40. Combination Sum II
  Difficulty: Medium

• 41. First Missing Positive
  Difficulty: Hard

• 410. Split Array Largest Sum
  Difficulty: Hard

• 414. Third Maximum Number
  Difficulty: Easy

• 42. Trapping Rain Water
  Difficulty: Hard

• 442. Find All Duplicates in an Array
  Difficulty: Medium

• 448. Find All Numbers Disappeared in an Array
  Difficulty: Easy

• 455. Assign Cookies
  Difficulty: Easy

• 46. Permutations
  Difficulty: Medium

• 463. Island Perimeter
  Difficulty: Easy

• 48. Rotate Image
  Difficulty: Medium

• 485. Max Consecutive Ones
  Difficulty: Easy

• 49. Group Anagrams
  Difficulty: Medium

• 495. Teemo Attacking
  Difficulty: Easy

• 496. Next Greater Element I
  Difficulty: Easy

• 498. Diagonal Traverse
  Difficulty: Medium

• 500. Keyboard Row
  Difficulty: Easy

• 503. Next Greater Element II
  Difficulty: Medium

• 506. Relative Ranks
  Difficulty: Easy

• 51. N-Queens
  Difficulty: Hard

• 523. Continuous Subarray Sum
  Difficulty: Medium

• 525. Contiguous Array
  Difficulty: Medium

• 54. Spiral Matrix
  Difficulty: Medium

• 540. Single Element in a Sorted Array
  Difficulty: Medium

• 542. 01 Matrix
  Difficulty: Medium

• 56. Merge Intervals
  Difficulty: Medium

• 560. Subarray Sum Equals K
  Difficulty: Medium

• 561. Array Partition
  Difficulty: Easy

• 575. Distribute Candies
  Difficulty: Easy

• 59. Spiral Matrix II
  Difficulty: Medium

• 594. Longest Harmonious Subsequence
  Difficulty: Easy

• 598. Range Addition II
  Difficulty: Easy

• 599. Minimum Index Sum of Two Lists
  Difficulty: Easy

• 605. Can Place Flowers
  Difficulty: Easy

• 621. Task Scheduler
  Difficulty: Medium

• 643. Maximum Average Subarray I
  Difficulty: Easy

• 658. Find K Closest Elements
  Difficulty: Medium

• 66. Plus One
  Difficulty: Easy

• 682. Baseball Game
  Difficulty: Easy

• 695. Max Area of Island
  Difficulty: Medium

• 724. Find Pivot Index
  Difficulty: Easy

• 733. Flood Fill
  Difficulty: Easy

• 735. Asteroid Collision
  Difficulty: Medium

• 739. Daily Temperatures
  Difficulty: Medium

• 74. Search a 2D Matrix
  Difficulty: Medium

• 75. Sort Colors
  Difficulty: Medium

• 79. Word Search
  Difficulty: Medium

• 792. Binary Search
  Difficulty: Easy

• 81. Search in Rotated Sorted Array II
  Difficulty: Medium

• 816. Design HashSet
  Difficulty: Easy

• 817. Design HashMap
  Difficulty: Easy

• 822. Unique Morse Code Words
  Difficulty: Easy

• 84. Largest Rectangle in Histogram
  Difficulty: Hard

• 841. Shortest Distance to a Character
  Difficulty: Easy

• 860. Design Circular Queue
  Difficulty: Medium

• 861. Flipping an Image
  Difficulty: Easy

• 88. Merge Sorted Array
  Difficulty: Easy

• 883. Car Fleet
  Difficulty: Medium

• 890. Lemonade Change
  Difficulty: Easy

• 898. Transpose Matrix
  Difficulty: Easy

• 907. Koko Eating Bananas
  Difficulty: Medium

• 917. Boats to Save People
  Difficulty: Medium

• 940. Fruit Into Baskets
  Difficulty: Medium

• 941. Sort Array By Parity
  Difficulty: Easy

• 944. Smallest Range I
  Difficulty: Easy

• 948. Sort an Array
  Difficulty: Medium

• 958. Sort Array By Parity II
  Difficulty: Easy

• 966. Binary Subarrays With Sum
  Difficulty: Medium

Backtracking (Total: 14)

• 17. Letter Combinations of a Phone Number
  Difficulty: Medium

• 1993. Sum of All Subset XOR Totals
  Difficulty: Easy

• 216. Combination Sum III
  Difficulty: Medium

• 22. Generate Parentheses
  Difficulty: Medium

• 257. Binary Tree Paths
  Difficulty: Easy

• 39. Combination Sum
  Difficulty: Medium

• 40. Combination Sum II
  Difficulty: Medium

• 401. Binary Watch
  Difficulty: Easy

• 46. Permutations
  Difficulty: Medium

• 51. N-Queens
  Difficulty: Hard

• 52. N-Queens II
  Difficulty: Hard

• 77. Combinations
  Difficulty: Medium

• 79. Word Search
  Difficulty: Medium

• 813. All Paths From Source to Target
  Difficulty: Medium

Binary Search (Total: 46)

• 1046. Max Consecutive Ones III
  Difficulty: Medium

• 1056. Capacity To Ship Packages Within D Days
  Difficulty: Medium

• 1321. Get Equal Substrings Within Budget
  Difficulty: Medium

• 1408. Find the Smallest Divisor Given a Threshold
  Difficulty: Medium

• 1468. Check If N and Its Double Exist
  Difficulty: Easy

• 153. Find Minimum in Rotated Sorted Array
  Difficulty: Medium

• 154. Find Minimum in Rotated Sorted Array II
  Difficulty: Hard

• 1605. Minimum Number of Days to Make m Bouquets
  Difficulty: Medium

• 1615. Range Sum of Sorted Subarray Sums
  Difficulty: Medium

• 162. Find Peak Element
  Difficulty: Medium

• 1646. Kth Missing Positive Number
  Difficulty: Easy

• 167. Two Sum II - Input Array Is Sorted
  Difficulty: Medium

• 1675. Magnetic Force Between Two Balls
  Difficulty: Medium

• 1776. Minimum Operations to Reduce X to Zero
  Difficulty: Medium

• 1918. Maximum Score of a Good Subarray
  Difficulty: Hard

• 2000. Minimum Speed to Arrive on Time
  Difficulty: Medium

• 2047. Find a Peak Element II
  Difficulty: Medium

• 209. Minimum Size Subarray Sum
  Difficulty: Medium

• 2134. Maximize the Confusion of an Exam
  Difficulty: Medium

• 222. Count Complete Tree Nodes
  Difficulty: Easy

• 2294. Minimum Time to Complete Trips
  Difficulty: Medium

• 2394. Count Subarrays With Score Less Than K
  Difficulty: Hard

• 240. Search a 2D Matrix II
  Difficulty: Medium

• 2530. Minimize Maximum of Array
  Difficulty: Medium

• 2614. Maximum Count of Positive Integer and Negative Integer
  Difficulty: Easy

• 2634. Minimum Common Value
  Difficulty: Easy

• 268. Missing Number
  Difficulty: Easy

• 278. First Bad Version
  Difficulty: Easy

• 33. Search in Rotated Sorted Array
  Difficulty: Medium

• 34. Find First and Last Position of Element in Sorted Array
  Difficulty: Medium

• 349. Intersection of Two Arrays
  Difficulty: Easy

• 35. Search Insert Position
  Difficulty: Easy

• 350. Intersection of Two Arrays II
  Difficulty: Easy

• 367. Valid Perfect Square
  Difficulty: Easy

• 374. Guess Number Higher or Lower
  Difficulty: Easy

• 4. Median of Two Sorted Arrays
  Difficulty: Hard

• 410. Split Array Largest Sum
  Difficulty: Hard

• 441. Arranging Coins
  Difficulty: Easy

• 540. Single Element in a Sorted Array
  Difficulty: Medium

• 633. Sum of Square Numbers
  Difficulty: Medium

• 658. Find K Closest Elements
  Difficulty: Medium

• 69. Sqrt(x)
  Difficulty: Easy

• 74. Search a 2D Matrix
  Difficulty: Medium

• 792. Binary Search
  Difficulty: Easy

• 81. Search in Rotated Sorted Array II
  Difficulty: Medium

• 907. Koko Eating Bananas
  Difficulty: Medium

Binary Search Tree (Total: 9)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 108. Convert Sorted Array to Binary Search Tree
  Difficulty: Easy

• 450. Delete Node in a BST
  Difficulty: Medium

• 501. Find Mode in Binary Search Tree
  Difficulty: Easy

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 783. Search in a Binary Search Tree
  Difficulty: Easy

• 789. Kth Largest Element in a Stream
  Difficulty: Easy

• 975. Range Sum of BST
  Difficulty: Easy

• 98. Validate Binary Search Tree
  Difficulty: Medium

Binary Tree (Total: 33)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 100. Same Tree
  Difficulty: Easy

• 101. Symmetric Tree
  Difficulty: Easy

• 102. Binary Tree Level Order Traversal
  Difficulty: Medium

• 1035. Cousins in Binary Tree
  Difficulty: Easy

• 104. Maximum Depth of Binary Tree
  Difficulty: Easy

• 105. Construct Binary Tree from Preorder and Inorder Traversal
  Difficulty: Medium

• 108. Convert Sorted Array to Binary Search Tree
  Difficulty: Easy

• 110. Balanced Binary Tree
  Difficulty: Easy

• 111. Minimum Depth of Binary Tree
  Difficulty: Easy

• 112. Path Sum
  Difficulty: Easy

• 1254. Deepest Leaves Sum
  Difficulty: Medium

• 144. Binary Tree Preorder Traversal
  Difficulty: Easy

• 145. Binary Tree Postorder Traversal
  Difficulty: Easy

• 222. Count Complete Tree Nodes
  Difficulty: Easy

• 226. Invert Binary Tree
  Difficulty: Easy

• 2416. Evaluate Boolean Binary Tree
  Difficulty: Easy

• 257. Binary Tree Paths
  Difficulty: Easy

• 404. Sum of Left Leaves
  Difficulty: Easy

• 450. Delete Node in a BST
  Difficulty: Medium

• 501. Find Mode in Binary Search Tree
  Difficulty: Easy

• 513. Find Bottom Left Tree Value
  Difficulty: Medium

• 543. Diameter of Binary Tree
  Difficulty: Easy

• 563. Binary Tree Tilt
  Difficulty: Easy

• 572. Subtree of Another Tree
  Difficulty: Easy

• 617. Merge Two Binary Trees
  Difficulty: Easy

• 637. Average of Levels in Binary Tree
  Difficulty: Easy

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 783. Search in a Binary Search Tree
  Difficulty: Easy

• 789. Kth Largest Element in a Stream
  Difficulty: Easy

• 94. Binary Tree Inorder Traversal
  Difficulty: Easy

• 975. Range Sum of BST
  Difficulty: Easy

• 98. Validate Binary Search Tree
  Difficulty: Medium

Bit Manipulation (Total: 22)

• 136. Single Number
  Difficulty: Easy

• 187. Repeated DNA Sequences
  Difficulty: Medium

• 1873. Longest Nice Substring
  Difficulty: Easy

• 190. Reverse Bits
  Difficulty: Easy

• 191. Number of 1 Bits
  Difficulty: Easy

• 1993. Sum of All Subset XOR Totals
  Difficulty: Easy

• 222. Count Complete Tree Nodes
  Difficulty: Easy

• 2308. Divide Array Into Equal Pairs
  Difficulty: Easy

• 231. Power of Two
  Difficulty: Easy

• 2323. Minimum Bit Flips to Convert Number
  Difficulty: Easy

• 2478. Longest Nice Subarray
  Difficulty: Medium

• 268. Missing Number
  Difficulty: Easy

• 338. Counting Bits
  Difficulty: Easy

• 3381. Shortest Subarray With OR at Least K I
  Difficulty: Easy

• 342. Power of Four
  Difficulty: Easy

• 3600. Find the K-th Character in String Game I
  Difficulty: Easy

• 389. Find the Difference
  Difficulty: Easy

• 401. Binary Watch
  Difficulty: Easy

• 405. Convert a Number to Hexadecimal
  Difficulty: Easy

• 461. Hamming Distance
  Difficulty: Easy

• 67. Add Binary
  Difficulty: Easy

• 861. Flipping an Image
  Difficulty: Easy

Brainteaser (Total: 3)

• 1086. Divisor Game
  Difficulty: Easy

• 292. Nim Game
  Difficulty: Easy

• 319. Bulb Switcher
  Difficulty: Medium

Breadth-First Search (Total: 32)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 100. Same Tree
  Difficulty: Easy

• 101. Symmetric Tree
  Difficulty: Easy

• 102. Binary Tree Level Order Traversal
  Difficulty: Medium

• 1035. Cousins in Binary Tree
  Difficulty: Easy

• 1036. Rotting Oranges
  Difficulty: Medium

• 104. Maximum Depth of Binary Tree
  Difficulty: Easy

• 111. Minimum Depth of Binary Tree
  Difficulty: Easy

• 112. Path Sum
  Difficulty: Easy

• 1254. Deepest Leaves Sum
  Difficulty: Medium

• 130. Surrounded Regions
  Difficulty: Medium

• 1380. Number of Closed Islands
  Difficulty: Medium

• 1414. Shortest Path in a Grid with Obstacles Elimination
  Difficulty: Hard

• 1876. Map of Highest Peak
  Difficulty: Medium

• 200. Number of Islands
  Difficulty: Medium

• 2103. Find All Groups of Farmland
  Difficulty: Medium

• 2121. Find if Path Exists in Graph
  Difficulty: Easy

• 226. Invert Binary Tree
  Difficulty: Easy

• 2375. Minimum Obstacle Removal to Reach Corner
  Difficulty: Hard

• 3558. Find a Safe Walk Through a Grid
  Difficulty: Medium

• 365. Water and Jug Problem
  Difficulty: Medium

• 404. Sum of Left Leaves
  Difficulty: Easy

• 463. Island Perimeter
  Difficulty: Easy

• 513. Find Bottom Left Tree Value
  Difficulty: Medium

• 542. 01 Matrix
  Difficulty: Medium

• 617. Merge Two Binary Trees
  Difficulty: Easy

• 637. Average of Levels in Binary Tree
  Difficulty: Easy

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 695. Max Area of Island
  Difficulty: Medium

• 733. Flood Fill
  Difficulty: Easy

• 774. Maximum Depth of N-ary Tree
  Difficulty: Easy

• 813. All Paths From Source to Target
  Difficulty: Medium

Bucket Sort (Total: 3)

• 164. Maximum Gap
  Difficulty: Medium

• 347. Top K Frequent Elements
  Difficulty: Medium

• 948. Sort an Array
  Difficulty: Medium

Combinatorics (Total: 1)

• 1993. Sum of All Subset XOR Totals
  Difficulty: Easy

Counting (Total: 25)

• 1034. Subarrays with K Different Integers
  Difficulty: Hard

• 1227. Number of Equivalent Domino Pairs
  Difficulty: Easy

• 1354. Find Players With Zero or One Losses
  Difficulty: Medium

• 1510. Find Lucky Integer in an Array
  Difficulty: Easy

• 169. Majority Element
  Difficulty: Easy

• 1708. Design Parking System
  Difficulty: Easy

• 1848. Sum of Unique Elements
  Difficulty: Easy

• 229. Majority Element II
  Difficulty: Medium

• 2308. Divide Array Into Equal Pairs
  Difficulty: Easy

• 2331. Intersection of Multiple Arrays
  Difficulty: Easy

• 2377. Check if Number Has Equal Digit Count and Digit Value
  Difficulty: Easy

• 2486. Most Frequent Even Element
  Difficulty: Easy

• 2532. Remove Letter To Equalize Frequency
  Difficulty: Easy

• 2614. Maximum Count of Positive Integer and Negative Integer
  Difficulty: Easy

• 299. Bulls and Cows
  Difficulty: Medium

• 347. Top K Frequent Elements
  Difficulty: Medium

• 3736. Find Valid Pair of Adjacent Digits in String
  Difficulty: Easy

• 3753. Maximum Difference Between Even and Odd Frequency I
  Difficulty: Easy

• 3778. Transform Array by Parity
  Difficulty: Easy

• 383. Ransom Note
  Difficulty: Easy

• 387. First Unique Character in a String
  Difficulty: Easy

• 3871. Minimum Deletions for At Most K Distinct Characters
  Difficulty: Easy

• 3872. Find Most Frequent Vowel and Consonant
  Difficulty: Easy

• 594. Longest Harmonious Subsequence
  Difficulty: Easy

• 621. Task Scheduler
  Difficulty: Medium

Counting Sort (Total: 2)

• 561. Array Partition
  Difficulty: Easy

• 948. Sort an Array
  Difficulty: Medium

Data Stream (Total: 5)

• 1477. Product of the Last K Numbers
  Difficulty: Medium

• 1582. Design Browser History
  Difficulty: Medium

• 789. Kth Largest Element in a Stream
  Difficulty: Easy

• 937. Online Stock Span
  Difficulty: Medium

• 969. Number of Recent Calls
  Difficulty: Easy

Database (Total: 13)

• 1625. Group Sold Products By The Date
  Difficulty: Easy

• 175. Combine Two Tables
  Difficulty: Easy

• 176. Second Highest Salary
  Difficulty: Medium

• 177. Nth Highest Salary
  Difficulty: Medium

• 178. Rank Scores
  Difficulty: Medium

• 181. Employees Earning More Than Their Managers
  Difficulty: Easy

• 182. Duplicate Emails
  Difficulty: Easy

• 183. Customers Who Never Order
  Difficulty: Easy

• 1908. Recyclable and Low Fat Products
  Difficulty: Easy

• 196. Delete Duplicate Emails
  Difficulty: Easy

• 577. Employee Bonus
  Difficulty: Easy

• 595. Big Countries
  Difficulty: Easy

• 620. Not Boring Movies
  Difficulty: Easy

Depth-First Search (Total: 42)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 100. Same Tree
  Difficulty: Easy

• 101. Symmetric Tree
  Difficulty: Easy

• 1035. Cousins in Binary Tree
  Difficulty: Easy

• 104. Maximum Depth of Binary Tree
  Difficulty: Easy

• 110. Balanced Binary Tree
  Difficulty: Easy

• 111. Minimum Depth of Binary Tree
  Difficulty: Easy

• 112. Path Sum
  Difficulty: Easy

• 1254. Deepest Leaves Sum
  Difficulty: Medium

• 130. Surrounded Regions
  Difficulty: Medium

• 1380. Number of Closed Islands
  Difficulty: Medium

• 144. Binary Tree Preorder Traversal
  Difficulty: Easy

• 145. Binary Tree Postorder Traversal
  Difficulty: Easy

• 200. Number of Islands
  Difficulty: Medium

• 2103. Find All Groups of Farmland
  Difficulty: Medium

• 2121. Find if Path Exists in Graph
  Difficulty: Easy

• 226. Invert Binary Tree
  Difficulty: Easy

• 2416. Evaluate Boolean Binary Tree
  Difficulty: Easy

• 257. Binary Tree Paths
  Difficulty: Easy

• 365. Water and Jug Problem
  Difficulty: Medium

• 386. Lexicographical Numbers
  Difficulty: Medium

• 404. Sum of Left Leaves
  Difficulty: Easy

• 463. Island Perimeter
  Difficulty: Easy

• 501. Find Mode in Binary Search Tree
  Difficulty: Easy

• 513. Find Bottom Left Tree Value
  Difficulty: Medium

• 543. Diameter of Binary Tree
  Difficulty: Easy

• 563. Binary Tree Tilt
  Difficulty: Easy

• 572. Subtree of Another Tree
  Difficulty: Easy

• 617. Merge Two Binary Trees
  Difficulty: Easy

• 637. Average of Levels in Binary Tree
  Difficulty: Easy

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 695. Max Area of Island
  Difficulty: Medium

• 733. Flood Fill
  Difficulty: Easy

• 766. Flatten a Multilevel Doubly Linked List
  Difficulty: Medium

• 774. Maximum Depth of N-ary Tree
  Difficulty: Easy

• 775. N-ary Tree Preorder Traversal
  Difficulty: Easy

• 776. N-ary Tree Postorder Traversal
  Difficulty: Easy

• 79. Word Search
  Difficulty: Medium

• 813. All Paths From Source to Target
  Difficulty: Medium

• 94. Binary Tree Inorder Traversal
  Difficulty: Easy

• 975. Range Sum of BST
  Difficulty: Easy

• 98. Validate Binary Search Tree
  Difficulty: Medium

Design (Total: 19)

• 1477. Product of the Last K Numbers
  Difficulty: Medium

• 1497. Design a Stack With Increment Operation
  Difficulty: Medium

• 155. Min Stack
  Difficulty: Medium

• 1582. Design Browser History
  Difficulty: Medium

• 1708. Design Parking System
  Difficulty: Easy

• 208. Implement Trie (Prefix Tree)
  Difficulty: Medium

• 225. Implement Stack using Queues
  Difficulty: Easy

• 232. Implement Queue using Stacks
  Difficulty: Easy

• 2429. Design a Food Rating System
  Difficulty: Medium

• 303. Range Sum Query - Immutable
  Difficulty: Easy

• 304. Range Sum Query 2D - Immutable
  Difficulty: Medium

• 355. Design Twitter
  Difficulty: Medium

• 789. Kth Largest Element in a Stream
  Difficulty: Easy

• 816. Design HashSet
  Difficulty: Easy

• 817. Design HashMap
  Difficulty: Easy

• 838. Design Linked List
  Difficulty: Medium

• 860. Design Circular Queue
  Difficulty: Medium

• 937. Online Stock Span
  Difficulty: Medium

• 969. Number of Recent Calls
  Difficulty: Easy

Divide and Conquer (Total: 14)

• 105. Construct Binary Tree from Preorder and Inorder Traversal
  Difficulty: Medium

• 108. Convert Sorted Array to Binary Search Tree
  Difficulty: Easy

• 148. Sort List
  Difficulty: Medium

• 169. Majority Element
  Difficulty: Easy

• 1873. Longest Nice Substring
  Difficulty: Easy

• 190. Reverse Bits
  Difficulty: Easy

• 191. Number of 1 Bits
  Difficulty: Easy

• 215. Kth Largest Element in an Array
  Difficulty: Medium

• 23. Merge k Sorted Lists
  Difficulty: Hard

• 240. Search a 2D Matrix II
  Difficulty: Medium

• 347. Top K Frequent Elements
  Difficulty: Medium

• 372. Super Pow
  Difficulty: Medium

• 4. Median of Two Sorted Arrays
  Difficulty: Hard

• 948. Sort an Array
  Difficulty: Medium

Doubly-Linked List (Total: 2)

• 1582. Design Browser History
  Difficulty: Medium

• 766. Flatten a Multilevel Doubly Linked List
  Difficulty: Medium

Dynamic Programming (Total: 19)

• 1013. Fibonacci Number
  Difficulty: Easy

• 1086. Divisor Game
  Difficulty: Easy

• 118. Pascal's Triangle
  Difficulty: Easy

• 119. Pascal's Triangle II
  Difficulty: Easy

• 121. Best Time to Buy and Sell Stock
  Difficulty: Easy

• 1236. N-th Tribonacci Number
  Difficulty: Easy

• 1586. Longest Subarray of 1's After Deleting One Element
  Difficulty: Medium

• 198. House Robber
  Difficulty: Medium

• 22. Generate Parentheses
  Difficulty: Medium

• 2530. Minimize Maximum of Array
  Difficulty: Medium

• 264. Ugly Number II
  Difficulty: Medium

• 338. Counting Bits
  Difficulty: Easy

• 392. Is Subsequence
  Difficulty: Easy

• 410. Split Array Largest Sum
  Difficulty: Hard

• 42. Trapping Rain Water
  Difficulty: Hard

• 5. Longest Palindromic Substring
  Difficulty: Medium

• 542. 01 Matrix
  Difficulty: Medium

• 650. 2 Keys Keyboard
  Difficulty: Medium

• 70. Climbing Stairs
  Difficulty: Easy

Enumeration (Total: 6)

• 1656. Count Good Triplets
  Difficulty: Easy

• 1993. Sum of All Subset XOR Totals
  Difficulty: Easy

• 204. Count Primes
  Difficulty: Medium

• 2351. Number of Ways to Buy Pens and Pencils
  Difficulty: Medium

• 2998. Count Symmetric Integers
  Difficulty: Easy

• 3849. Equal Sum Grid Partition I
  Difficulty: Medium

Game Theory (Total: 2)

• 1086. Divisor Game
  Difficulty: Easy

• 292. Nim Game
  Difficulty: Easy

Geometry (Total: 1)

• 1349. Check If It Is a Straight Line
  Difficulty: Easy

Graph (Total: 5)

• 1916. Find Center of Star Graph
  Difficulty: Easy

• 2121. Find if Path Exists in Graph
  Difficulty: Easy

• 2375. Minimum Obstacle Removal to Reach Corner
  Difficulty: Hard

• 3558. Find a Safe Walk Through a Grid
  Difficulty: Medium

• 813. All Paths From Source to Target
  Difficulty: Medium

Greedy (Total: 23)

• 1018. Largest Perimeter Triangle
  Difficulty: Easy

• 1033. Broken Calculator
  Difficulty: Medium

• 11. Container With Most Water
  Difficulty: Medium

• 1159. Smallest Subsequence of Distinct Characters
  Difficulty: Medium

• 1329. Minimum Cost to Move Chips to The Same Position
  Difficulty: Easy

• 1448. Maximum 69 Number
  Difficulty: Easy

• 2245. Destroying Asteroids
  Difficulty: Medium

• 2436. Make Array Zero by Subtracting Equal Amounts
  Difficulty: Easy

• 2530. Minimize Maximum of Array
  Difficulty: Medium

• 2650. Split With Minimum Sum
  Difficulty: Easy

• 316. Remove Duplicate Letters
  Difficulty: Medium

• 3871. Minimum Deletions for At Most K Distinct Characters
  Difficulty: Easy

• 402. Remove K Digits
  Difficulty: Medium

• 409. Longest Palindrome
  Difficulty: Easy

• 410. Split Array Largest Sum
  Difficulty: Hard

• 455. Assign Cookies
  Difficulty: Easy

• 561. Array Partition
  Difficulty: Easy

• 605. Can Place Flowers
  Difficulty: Easy

• 621. Task Scheduler
  Difficulty: Medium

• 670. Maximum Swap
  Difficulty: Medium

• 768. Partition Labels
  Difficulty: Medium

• 890. Lemonade Change
  Difficulty: Easy

• 917. Boats to Save People
  Difficulty: Medium

Hash Function (Total: 4)

• 187. Repeated DNA Sequences
  Difficulty: Medium

• 572. Subtree of Another Tree
  Difficulty: Easy

• 816. Design HashSet
  Difficulty: Easy

• 817. Design HashMap
  Difficulty: Easy

Hash Table (Total: 96)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 1. Two Sum
  Difficulty: Easy

• 1034. Subarrays with K Different Integers
  Difficulty: Hard

• 1044. Find Common Characters
  Difficulty: Easy

• 105. Construct Binary Tree from Preorder and Inorder Traversal
  Difficulty: Medium

• 12. Integer to Roman
  Difficulty: Medium

• 1227. Number of Equivalent Domino Pairs
  Difficulty: Easy

• 128. Longest Consecutive Sequence
  Difficulty: Medium

• 13. Roman to Integer
  Difficulty: Easy

• 1353. Find Resultant Array After Removing Anagrams
  Difficulty: Easy

• 1354. Find Players With Zero or One Losses
  Difficulty: Medium

• 1370. Count Number of Nice Subarrays
  Difficulty: Medium

• 1392. Find the Difference of Two Arrays
  Difficulty: Easy

• 141. Linked List Cycle
  Difficulty: Easy

• 142. Linked List Cycle II
  Difficulty: Medium

• 1468. Check If N and Its Double Exist
  Difficulty: Easy

• 1500. Count Largest Group
  Difficulty: Easy

• 1510. Find Lucky Integer in an Array
  Difficulty: Easy

• 160. Intersection of Two Linked Lists
  Difficulty: Easy

• 169. Majority Element
  Difficulty: Easy

• 17. Letter Combinations of a Phone Number
  Difficulty: Medium

• 1741. Sort Array by Increasing Frequency
  Difficulty: Easy

• 1776. Minimum Operations to Reduce X to Zero
  Difficulty: Medium

• 1848. Sum of Unique Elements
  Difficulty: Easy

• 187. Repeated DNA Sequences
  Difficulty: Medium

• 1873. Longest Nice Substring
  Difficulty: Easy

• 202. Happy Number
  Difficulty: Easy

• 205. Isomorphic Strings
  Difficulty: Easy

• 208. Implement Trie (Prefix Tree)
  Difficulty: Medium

• 217. Contains Duplicate
  Difficulty: Easy

• 219. Contains Duplicate II
  Difficulty: Easy

• 229. Majority Element II
  Difficulty: Medium

• 2308. Divide Array Into Equal Pairs
  Difficulty: Easy

• 2331. Intersection of Multiple Arrays
  Difficulty: Easy

• 2377. Check if Number Has Equal Digit Count and Digit Value
  Difficulty: Easy

• 242. Valid Anagram
  Difficulty: Easy

• 2429. Design a Food Rating System
  Difficulty: Medium

• 2436. Make Array Zero by Subtracting Equal Amounts
  Difficulty: Easy

• 2486. Most Frequent Even Element
  Difficulty: Easy

• 2532. Remove Letter To Equalize Frequency
  Difficulty: Easy

• 2552. Maximum Sum of Distinct Subarrays With Length K
  Difficulty: Medium

• 2581. Divide Players Into Teams of Equal Skill
  Difficulty: Medium

• 2599. Take K of Each Character From Left and Right
  Difficulty: Medium

• 2609. Distinct Prime Factors of Product of Array
  Difficulty: Medium

• 2626. Count the Number of Good Subarrays
  Difficulty: Medium

• 2634. Minimum Common Value
  Difficulty: Easy

• 264. Ugly Number II
  Difficulty: Medium

• 268. Missing Number
  Difficulty: Easy

• 2721. Sum of Distances
  Difficulty: Medium

• 2751. Sliding Subarray Beauty
  Difficulty: Medium

• 2791. Find the Losers of the Circular Game
  Difficulty: Easy

• 290. Word Pattern
  Difficulty: Easy

• 299. Bulls and Cows
  Difficulty: Medium

• 3. Longest Substring Without Repeating Characters
  Difficulty: Medium

• 30. Substring with Concatenation of All Words
  Difficulty: Hard

• 3236. Smallest Missing Integer Greater Than Sequential Prefix Sum
  Difficulty: Easy

• 347. Top K Frequent Elements
  Difficulty: Medium

• 349. Intersection of Two Arrays
  Difficulty: Easy

• 350. Intersection of Two Arrays II
  Difficulty: Easy

• 355. Design Twitter
  Difficulty: Medium

• 3581. The Two Sneaky Numbers of Digitville
  Difficulty: Easy

• 36. Valid Sudoku
  Difficulty: Medium

• 3656. Minimum Number of Operations to Make Elements in Array Distinct
  Difficulty: Easy

• 3736. Find Valid Pair of Adjacent Digits in String
  Difficulty: Easy

• 3753. Maximum Difference Between Even and Odd Frequency I
  Difficulty: Easy

• 383. Ransom Note
  Difficulty: Easy

• 387. First Unique Character in a String
  Difficulty: Easy

• 3871. Minimum Deletions for At Most K Distinct Characters
  Difficulty: Easy

• 3872. Find Most Frequent Vowel and Consonant
  Difficulty: Easy

• 389. Find the Difference
  Difficulty: Easy

• 409. Longest Palindrome
  Difficulty: Easy

• 41. First Missing Positive
  Difficulty: Hard

• 424. Longest Repeating Character Replacement
  Difficulty: Medium

• 438. Find All Anagrams in a String
  Difficulty: Medium

• 442. Find All Duplicates in an Array
  Difficulty: Medium

• 448. Find All Numbers Disappeared in an Array
  Difficulty: Easy

• 49. Group Anagrams
  Difficulty: Medium

• 496. Next Greater Element I
  Difficulty: Easy

• 500. Keyboard Row
  Difficulty: Easy

• 523. Continuous Subarray Sum
  Difficulty: Medium

• 525. Contiguous Array
  Difficulty: Medium

• 560. Subarray Sum Equals K
  Difficulty: Medium

• 567. Permutation in String
  Difficulty: Medium

• 575. Distribute Candies
  Difficulty: Easy

• 594. Longest Harmonious Subsequence
  Difficulty: Easy

• 599. Minimum Index Sum of Two Lists
  Difficulty: Easy

• 621. Task Scheduler
  Difficulty: Medium

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 76. Minimum Window Substring
  Difficulty: Hard

• 768. Partition Labels
  Difficulty: Medium

• 782. Jewels and Stones
  Difficulty: Easy

• 816. Design HashSet
  Difficulty: Easy

• 817. Design HashMap
  Difficulty: Easy

• 822. Unique Morse Code Words
  Difficulty: Easy

• 940. Fruit Into Baskets
  Difficulty: Medium

• 966. Binary Subarrays With Sum
  Difficulty: Medium

Heap (Priority Queue) (Total: 16)

• 506. Relative Ranks
  Difficulty: Easy

• 1127. Last Stone Weight
  Difficulty: Easy

• 215. Kth Largest Element in an Array
  Difficulty: Medium

• 23. Merge k Sorted Lists
  Difficulty: Hard

• 2375. Minimum Obstacle Removal to Reach Corner
  Difficulty: Hard

• 2429. Design a Food Rating System
  Difficulty: Medium

• 2436. Make Array Zero by Subtracting Equal Amounts
  Difficulty: Easy

• 264. Ugly Number II
  Difficulty: Medium

• 347. Top K Frequent Elements
  Difficulty: Medium

• 355. Design Twitter
  Difficulty: Medium

• 3558. Find a Safe Walk Through a Grid
  Difficulty: Medium

• 506. Relative Ranks
  Difficulty: Easy

• 621. Task Scheduler
  Difficulty: Medium

• 658. Find K Closest Elements
  Difficulty: Medium

• 789. Kth Largest Element in a Stream
  Difficulty: Easy

• 948. Sort an Array
  Difficulty: Medium

Interactive (Total: 2)

• 278. First Bad Version
  Difficulty: Easy

• 374. Guess Number Higher or Lower
  Difficulty: Easy

Line Sweep (Total: 1)

• 1028. Interval List Intersections
  Difficulty: Medium

Linked List (Total: 27)

• 1072. Next Greater Node In Linked List
  Difficulty: Medium

• 141. Linked List Cycle
  Difficulty: Easy

• 142. Linked List Cycle II
  Difficulty: Medium

• 143. Reorder List
  Difficulty: Medium

• 148. Sort List
  Difficulty: Medium

• 1582. Design Browser History
  Difficulty: Medium

• 160. Intersection of Two Linked Lists
  Difficulty: Easy

• 19. Remove Nth Node From End of List
  Difficulty: Medium

• 2. Add Two Numbers
  Difficulty: Medium

• 203. Remove Linked List Elements
  Difficulty: Easy

• 206. Reverse Linked List
  Difficulty: Easy

• 21. Merge Two Sorted Lists
  Difficulty: Easy

• 23. Merge k Sorted Lists
  Difficulty: Hard

• 234. Palindrome Linked List
  Difficulty: Easy

• 24. Swap Nodes in Pairs
  Difficulty: Medium

• 25. Reverse Nodes in k-Group
  Difficulty: Hard

• 2871. Double a Number Represented as a Linked List
  Difficulty: Medium

• 355. Design Twitter
  Difficulty: Medium

• 528. Swapping Nodes in a Linked List
  Difficulty: Medium

• 61. Rotate List
  Difficulty: Medium

• 766. Flatten a Multilevel Doubly Linked List
  Difficulty: Medium

• 816. Design HashSet
  Difficulty: Easy

• 817. Design HashMap
  Difficulty: Easy

• 83. Remove Duplicates from Sorted List
  Difficulty: Easy

• 838. Design Linked List
  Difficulty: Medium

• 860. Design Circular Queue
  Difficulty: Medium

• 908. Middle of the Linked List
  Difficulty: Easy

Math (Total: 80)

• 1013. Fibonacci Number
  Difficulty: Easy

• 1018. Largest Perimeter Triangle
  Difficulty: Easy

• 1033. Broken Calculator
  Difficulty: Medium

• 1086. Divisor Game
  Difficulty: Easy

• 1195. Distribute Candies to People
  Difficulty: Easy

• 12. Integer to Roman
  Difficulty: Medium

• 1236. N-th Tribonacci Number
  Difficulty: Easy

• 13. Roman to Integer
  Difficulty: Easy

• 1329. Minimum Cost to Move Chips to The Same Position
  Difficulty: Easy

• 1349. Check If It Is a Straight Line
  Difficulty: Easy

• 1370. Count Number of Nice Subarrays
  Difficulty: Medium

• 1448. Maximum 69 Number
  Difficulty: Easy

• 1477. Product of the Last K Numbers
  Difficulty: Medium

• 150. Evaluate Reverse Polish Notation
  Difficulty: Medium

• 1500. Count Largest Group
  Difficulty: Easy

• 168. Excel Sheet Column Title
  Difficulty: Easy

• 171. Excel Sheet Column Number
  Difficulty: Easy

• 1787. Sum of Absolute Differences in a Sorted Array
  Difficulty: Medium

• 189. Rotate Array
  Difficulty: Medium

• 1951. Find the Winner of the Circular Game
  Difficulty: Medium

• 1965. Sum of Digits in Base K
  Difficulty: Easy

• 1993. Sum of All Subset XOR Totals
  Difficulty: Easy

• 2. Add Two Numbers
  Difficulty: Medium

• 202. Happy Number
  Difficulty: Easy

• 204. Count Primes
  Difficulty: Medium

• 2106. Find Greatest Common Divisor of Array
  Difficulty: Easy

• 227. Basic Calculator II
  Difficulty: Medium

• 2278. Find Three Consecutive Integers That Sum to a Given Number
  Difficulty: Medium

• 231. Power of Two
  Difficulty: Easy

• 2351. Number of Ways to Buy Pens and Pencils
  Difficulty: Medium

• 2383. Add Two Integers
  Difficulty: Easy

• 2546. Number of Subarrays With GCD Equal to K
  Difficulty: Medium

• 2557. Number of Subarrays With LCM Equal to K
  Difficulty: Medium

• 258. Add Digits
  Difficulty: Easy

• 2609. Distinct Prime Factors of Product of Array
  Difficulty: Medium

• 263. Ugly Number
  Difficulty: Easy

• 2630. Alternating Digit Sum
  Difficulty: Easy

• 264. Ugly Number II
  Difficulty: Medium

• 2645. Pass the Pillow
  Difficulty: Easy

• 2650. Split With Minimum Sum
  Difficulty: Easy

• 268. Missing Number
  Difficulty: Easy

• 2812. Find the Maximum Achievable Number
  Difficulty: Easy

• 2871. Double a Number Represented as a Linked List
  Difficulty: Medium

• 292. Nim Game
  Difficulty: Easy

• 2998. Count Symmetric Integers
  Difficulty: Easy

• 319. Bulb Switcher
  Difficulty: Medium

• 3234. Double Modular Exponentiation
  Difficulty: Medium

• 326. Power of Three
  Difficulty: Easy

• 3321. Type of Triangle
  Difficulty: Easy

• 3367. Find the Sum of Encrypted Integers
  Difficulty: Easy

• 342. Power of Four
  Difficulty: Easy

• 3450. Find the Child Who Has the Ball After K Seconds
  Difficulty: Easy

• 3581. The Two Sneaky Numbers of Digitville
  Difficulty: Easy

• 3600. Find the K-th Character in String Game I
  Difficulty: Easy

• 3625. Stone Removal Game
  Difficulty: Easy

• 365. Water and Jug Problem
  Difficulty: Medium

• 367. Valid Perfect Square
  Difficulty: Easy

• 372. Super Pow
  Difficulty: Medium

• 405. Convert a Number to Hexadecimal
  Difficulty: Easy

• 412. Fizz Buzz
  Difficulty: Easy

• 415. Add Strings
  Difficulty: Easy

• 43. Multiply Strings
  Difficulty: Medium

• 441. Arranging Coins
  Difficulty: Easy

• 48. Rotate Image
  Difficulty: Medium

• 492. Construct the Rectangle
  Difficulty: Easy

• 50. Pow(x, n)
  Difficulty: Medium

• 507. Perfect Number
  Difficulty: Easy

• 523. Continuous Subarray Sum
  Difficulty: Medium

• 598. Range Addition II
  Difficulty: Easy

• 633. Sum of Square Numbers
  Difficulty: Medium

• 650. 2 Keys Keyboard
  Difficulty: Medium

• 66. Plus One
  Difficulty: Easy

• 67. Add Binary
  Difficulty: Easy

• 670. Maximum Swap
  Difficulty: Medium

• 69. Sqrt(x)
  Difficulty: Easy

• 7. Reverse Integer
  Difficulty: Medium

• 70. Climbing Stairs
  Difficulty: Easy

• 728. Self Dividing Numbers
  Difficulty: Easy

• 9. Palindrome Number
  Difficulty: Easy

• 944. Smallest Range I
  Difficulty: Easy

Matrix (Total: 30)

• 1036. Rotting Oranges
  Difficulty: Medium

• 1242. Matrix Block Sum
  Difficulty: Medium

• 130. Surrounded Regions
  Difficulty: Medium

• 1380. Number of Closed Islands
  Difficulty: Medium

• 1414. Shortest Path in a Grid with Obstacles Elimination
  Difficulty: Hard

• 1677. Matrix Diagonal Sum
  Difficulty: Easy

• 1791. Richest Customer Wealth
  Difficulty: Easy

• 1876. Map of Highest Peak
  Difficulty: Medium

• 200. Number of Islands
  Difficulty: Medium

• 2047. Find a Peak Element II
  Difficulty: Medium

• 2103. Find All Groups of Farmland
  Difficulty: Medium

• 2375. Minimum Obstacle Removal to Reach Corner
  Difficulty: Hard

• 240. Search a 2D Matrix II
  Difficulty: Medium

• 304. Range Sum Query 2D - Immutable
  Difficulty: Medium

• 3558. Find a Safe Walk Through a Grid
  Difficulty: Medium

• 36. Valid Sudoku
  Difficulty: Medium

• 3849. Equal Sum Grid Partition I
  Difficulty: Medium

• 3973. Flip Square Submatrix Vertically
  Difficulty: Easy

• 463. Island Perimeter
  Difficulty: Easy

• 48. Rotate Image
  Difficulty: Medium

• 498. Diagonal Traverse
  Difficulty: Medium

• 54. Spiral Matrix
  Difficulty: Medium

• 542. 01 Matrix
  Difficulty: Medium

• 59. Spiral Matrix II
  Difficulty: Medium

• 695. Max Area of Island
  Difficulty: Medium

• 733. Flood Fill
  Difficulty: Easy

• 74. Search a 2D Matrix
  Difficulty: Medium

• 79. Word Search
  Difficulty: Medium

• 861. Flipping an Image
  Difficulty: Easy

• 898. Transpose Matrix
  Difficulty: Easy

Memoization (Total: 3)

• 1013. Fibonacci Number
  Difficulty: Easy

• 1236. N-th Tribonacci Number
  Difficulty: Easy

• 70. Climbing Stairs
  Difficulty: Easy

Merge Sort (Total: 3)

• 148. Sort List
  Difficulty: Medium

• 23. Merge k Sorted Lists
  Difficulty: Hard

• 948. Sort an Array
  Difficulty: Medium

Monotonic Queue (Total: 1)

• 2527. Count Subarrays With Fixed Bounds
  Difficulty: Hard

Monotonic Stack (Total: 12)

• 1072. Next Greater Node In Linked List
  Difficulty: Medium

• 1159. Smallest Subsequence of Distinct Characters
  Difficulty: Medium

• 1918. Maximum Score of a Good Subarray
  Difficulty: Hard

• 316. Remove Duplicate Letters
  Difficulty: Medium

• 402. Remove K Digits
  Difficulty: Medium

• 42. Trapping Rain Water
  Difficulty: Hard

• 496. Next Greater Element I
  Difficulty: Easy

• 503. Next Greater Element II
  Difficulty: Medium

• 739. Daily Temperatures
  Difficulty: Medium

• 84. Largest Rectangle in Histogram
  Difficulty: Hard

• 883. Car Fleet
  Difficulty: Medium

• 937. Online Stock Span
  Difficulty: Medium

Number Theory (Total: 6)

• 204. Count Primes
  Difficulty: Medium

• 2106. Find Greatest Common Divisor of Array
  Difficulty: Easy

• 2546. Number of Subarrays With GCD Equal to K
  Difficulty: Medium

• 2557. Number of Subarrays With LCM Equal to K
  Difficulty: Medium

• 258. Add Digits
  Difficulty: Easy

• 2609. Distinct Prime Factors of Product of Array
  Difficulty: Medium

Ordered Set (Total: 1)

• 2429. Design a Food Rating System
  Difficulty: Medium

Prefix Sum (Total: 30)

• 1046. Max Consecutive Ones III
  Difficulty: Medium

• 1242. Matrix Block Sum
  Difficulty: Medium

• 1321. Get Equal Substrings Within Budget
  Difficulty: Medium

• 1370. Count Number of Nice Subarrays
  Difficulty: Medium

• 1477. Product of the Last K Numbers
  Difficulty: Medium

• 1603. Running Sum of 1d Array
  Difficulty: Easy

• 1615. Range Sum of Sorted Subarray Sums
  Difficulty: Medium

• 1776. Minimum Operations to Reduce X to Zero
  Difficulty: Medium

• 1787. Sum of Absolute Differences in a Sorted Array
  Difficulty: Medium

• 209. Minimum Size Subarray Sum
  Difficulty: Medium

• 2134. Maximize the Confusion of an Exam
  Difficulty: Medium

• 2249. Count the Hidden Sequences
  Difficulty: Medium

• 2342. Minimum Average Difference
  Difficulty: Medium

• 2358. Number of Ways to Split Array
  Difficulty: Medium

• 238. Product of Array Except Self
  Difficulty: Medium

• 2394. Count Subarrays With Score Less Than K
  Difficulty: Hard

• 2465. Shifting Letters II
  Difficulty: Medium

• 2530. Minimize Maximum of Array
  Difficulty: Medium

• 2714. Left and Right Sum Differences
  Difficulty: Easy

• 2721. Sum of Distances
  Difficulty: Medium

• 303. Range Sum Query - Immutable
  Difficulty: Easy

• 304. Range Sum Query 2D - Immutable
  Difficulty: Medium

• 3644. Minimum Positive Sum Subarray
  Difficulty: Easy

• 3849. Equal Sum Grid Partition I
  Difficulty: Medium

• 410. Split Array Largest Sum
  Difficulty: Hard

• 523. Continuous Subarray Sum
  Difficulty: Medium

• 525. Contiguous Array
  Difficulty: Medium

• 560. Subarray Sum Equals K
  Difficulty: Medium

• 724. Find Pivot Index
  Difficulty: Easy

• 966. Binary Subarrays With Sum
  Difficulty: Medium

Queue (Total: 7)

• 1951. Find the Winner of the Circular Game
  Difficulty: Medium

• 225. Implement Stack using Queues
  Difficulty: Easy

• 232. Implement Queue using Stacks
  Difficulty: Easy

• 2527. Count Subarrays With Fixed Bounds
  Difficulty: Hard

• 387. First Unique Character in a String
  Difficulty: Easy

• 860. Design Circular Queue
  Difficulty: Medium

• 969. Number of Recent Calls
  Difficulty: Easy

Quickselect (Total: 2)

• 215. Kth Largest Element in an Array
  Difficulty: Medium

• 347. Top K Frequent Elements
  Difficulty: Medium

Radix Sort (Total: 2)

• 164. Maximum Gap
  Difficulty: Medium

• 948. Sort an Array
  Difficulty: Medium

Recursion (Total: 15)

• 1013. Fibonacci Number
  Difficulty: Easy

• 143. Reorder List
  Difficulty: Medium

• 1951. Find the Winner of the Circular Game
  Difficulty: Medium

• 2. Add Two Numbers
  Difficulty: Medium

• 203. Remove Linked List Elements
  Difficulty: Easy

• 206. Reverse Linked List
  Difficulty: Easy

• 21. Merge Two Sorted Lists
  Difficulty: Easy

• 231. Power of Two
  Difficulty: Easy

• 234. Palindrome Linked List
  Difficulty: Easy

• 24. Swap Nodes in Pairs
  Difficulty: Medium

• 25. Reverse Nodes in k-Group
  Difficulty: Hard

• 326. Power of Three
  Difficulty: Easy

• 342. Power of Four
  Difficulty: Easy

• 3600. Find the K-th Character in String Game I
  Difficulty: Easy

• 50. Pow(x, n)
  Difficulty: Medium

Rolling Hash (Total: 1)

• 187. Repeated DNA Sequences
  Difficulty: Medium

Shortest Path (Total: 2)

• 2375. Minimum Obstacle Removal to Reach Corner
  Difficulty: Hard

• 3558. Find a Safe Walk Through a Grid
  Difficulty: Medium

Simulation (Total: 32)

• 1195. Distribute Candies to People
  Difficulty: Easy

• 1682. Most Visited Sector in a Circular Track
  Difficulty: Easy

• 1708. Design Parking System
  Difficulty: Easy

• 1951. Find the Winner of the Circular Game
  Difficulty: Medium

• 2137. Final Value of Variable After Performing Operations
  Difficulty: Easy

• 2265. Partition Array According to Given Pivot
  Difficulty: Medium

• 2278. Find Three Consecutive Integers That Sum to a Given Number
  Difficulty: Medium

• 2436. Make Array Zero by Subtracting Equal Amounts
  Difficulty: Easy

• 2470. Removing Stars From a String
  Difficulty: Medium

• 2551. Apply Operations to an Array
  Difficulty: Easy

• 258. Add Digits
  Difficulty: Easy

• 2645. Pass the Pillow
  Difficulty: Easy

• 2791. Find the Losers of the Circular Game
  Difficulty: Easy

• 3234. Double Modular Exponentiation
  Difficulty: Medium

• 3450. Find the Child Who Has the Ball After K Seconds
  Difficulty: Easy

• 3533. Snake in Matrix
  Difficulty: Easy

• 3600. Find the K-th Character in String Game I
  Difficulty: Easy

• 3625. Stone Removal Game
  Difficulty: Easy

• 3811. Reverse Degree of a String
  Difficulty: Easy

• 412. Fizz Buzz
  Difficulty: Easy

• 415. Add Strings
  Difficulty: Easy

• 43. Multiply Strings
  Difficulty: Medium

• 495. Teemo Attacking
  Difficulty: Easy

• 498. Diagonal Traverse
  Difficulty: Medium

• 54. Spiral Matrix
  Difficulty: Medium

• 59. Spiral Matrix II
  Difficulty: Medium

• 67. Add Binary
  Difficulty: Easy

• 682. Baseball Game
  Difficulty: Easy

• 735. Asteroid Collision
  Difficulty: Medium

• 861. Flipping an Image
  Difficulty: Easy

• 874. Backspace String Compare
  Difficulty: Easy

• 898. Transpose Matrix
  Difficulty: Easy

Sliding Window (Total: 36)

• 1034. Subarrays with K Different Integers
  Difficulty: Hard

• 1046. Max Consecutive Ones III
  Difficulty: Medium

• 1321. Get Equal Substrings Within Budget
  Difficulty: Medium

• 1351. Replace the Substring for Balanced String
  Difficulty: Medium

• 1370. Count Number of Nice Subarrays
  Difficulty: Medium

• 1567. Maximum Number of Vowels in a Substring of Given Length
  Difficulty: Medium

• 1586. Longest Subarray of 1's After Deleting One Element
  Difficulty: Medium

• 1755. Defuse the Bomb
  Difficulty: Easy

• 1776. Minimum Operations to Reduce X to Zero
  Difficulty: Medium

• 187. Repeated DNA Sequences
  Difficulty: Medium

• 1873. Longest Nice Substring
  Difficulty: Easy

• 209. Minimum Size Subarray Sum
  Difficulty: Medium

• 2134. Maximize the Confusion of an Exam
  Difficulty: Medium

• 219. Contains Duplicate II
  Difficulty: Easy

• 2211. K Radius Subarray Averages
  Difficulty: Medium

• 2394. Count Subarrays With Score Less Than K
  Difficulty: Hard

• 2478. Longest Nice Subarray
  Difficulty: Medium

• 2527. Count Subarrays With Fixed Bounds
  Difficulty: Hard

• 2552. Maximum Sum of Distinct Subarrays With Length K
  Difficulty: Medium

• 2599. Take K of Each Character From Left and Right
  Difficulty: Medium

• 2626. Count the Number of Good Subarrays
  Difficulty: Medium

• 2751. Sliding Subarray Beauty
  Difficulty: Medium

• 3. Longest Substring Without Repeating Characters
  Difficulty: Medium

• 30. Substring with Concatenation of All Words
  Difficulty: Hard

• 3213. Count Subarrays Where Max Element Appears at Least K Times
  Difficulty: Medium

• 3381. Shortest Subarray With OR at Least K I
  Difficulty: Easy

• 3644. Minimum Positive Sum Subarray
  Difficulty: Easy

• 424. Longest Repeating Character Replacement
  Difficulty: Medium

• 438. Find All Anagrams in a String
  Difficulty: Medium

• 567. Permutation in String
  Difficulty: Medium

• 594. Longest Harmonious Subsequence
  Difficulty: Easy

• 643. Maximum Average Subarray I
  Difficulty: Easy

• 658. Find K Closest Elements
  Difficulty: Medium

• 76. Minimum Window Substring
  Difficulty: Hard

• 940. Fruit Into Baskets
  Difficulty: Medium

• 966. Binary Subarrays With Sum
  Difficulty: Medium

Sorting (Total: 52)

• 506. Relative Ranks
  Difficulty: Easy

• 1018. Largest Perimeter Triangle
  Difficulty: Easy

• 1019. Squares of a Sorted Array
  Difficulty: Easy

• 1210. Mean of Array After Removing Some Elements
  Difficulty: Easy

• 1353. Find Resultant Array After Removing Anagrams
  Difficulty: Easy

• 1354. Find Players With Zero or One Losses
  Difficulty: Medium

• 1468. Check If N and Its Double Exist
  Difficulty: Easy

• 148. Sort List
  Difficulty: Medium

• 15. 3Sum
  Difficulty: Medium

• 16. 3Sum Closest
  Difficulty: Medium

• 1615. Range Sum of Sorted Subarray Sums
  Difficulty: Medium

• 164. Maximum Gap
  Difficulty: Medium

• 1675. Magnetic Force Between Two Balls
  Difficulty: Medium

• 169. Majority Element
  Difficulty: Easy

• 1741. Sort Array by Increasing Frequency
  Difficulty: Easy

• 18. 4Sum
  Difficulty: Medium

• 1970. Sorting the Sentence
  Difficulty: Easy

• 215. Kth Largest Element in an Array
  Difficulty: Medium

• 217. Contains Duplicate
  Difficulty: Easy

• 2245. Destroying Asteroids
  Difficulty: Medium

• 229. Majority Element II
  Difficulty: Medium

• 2331. Intersection of Multiple Arrays
  Difficulty: Easy

• 242. Valid Anagram
  Difficulty: Easy

• 2436. Make Array Zero by Subtracting Equal Amounts
  Difficulty: Easy

• 2581. Divide Players Into Teams of Equal Skill
  Difficulty: Medium

• 2650. Split With Minimum Sum
  Difficulty: Easy

• 268. Missing Number
  Difficulty: Easy

• 2836. Neither Minimum nor Maximum
  Difficulty: Easy

• 3236. Smallest Missing Integer Greater Than Sequential Prefix Sum
  Difficulty: Easy

• 3321. Type of Triangle
  Difficulty: Easy

• 347. Top K Frequent Elements
  Difficulty: Medium

• 349. Intersection of Two Arrays
  Difficulty: Easy

• 350. Intersection of Two Arrays II
  Difficulty: Easy

• 3778. Transform Array by Parity
  Difficulty: Easy

• 3871. Minimum Deletions for At Most K Distinct Characters
  Difficulty: Easy

• 389. Find the Difference
  Difficulty: Easy

• 414. Third Maximum Number
  Difficulty: Easy

• 455. Assign Cookies
  Difficulty: Easy

• 49. Group Anagrams
  Difficulty: Medium

• 506. Relative Ranks
  Difficulty: Easy

• 56. Merge Intervals
  Difficulty: Medium

• 561. Array Partition
  Difficulty: Easy

• 594. Longest Harmonious Subsequence
  Difficulty: Easy

• 621. Task Scheduler
  Difficulty: Medium

• 658. Find K Closest Elements
  Difficulty: Medium

• 75. Sort Colors
  Difficulty: Medium

• 88. Merge Sorted Array
  Difficulty: Easy

• 883. Car Fleet
  Difficulty: Medium

• 917. Boats to Save People
  Difficulty: Medium

• 941. Sort Array By Parity
  Difficulty: Easy

• 948. Sort an Array
  Difficulty: Medium

• 958. Sort Array By Parity II
  Difficulty: Easy

Stack (Total: 35)

• 1072. Next Greater Node In Linked List
  Difficulty: Medium

• 1128. Remove All Adjacent Duplicates In String
  Difficulty: Easy

• 1159. Smallest Subsequence of Distinct Characters
  Difficulty: Medium

• 1320. Remove All Adjacent Duplicates in String II
  Difficulty: Medium

• 143. Reorder List
  Difficulty: Medium

• 144. Binary Tree Preorder Traversal
  Difficulty: Easy

• 145. Binary Tree Postorder Traversal
  Difficulty: Easy

• 1497. Design a Stack With Increment Operation
  Difficulty: Medium

• 150. Evaluate Reverse Polish Notation
  Difficulty: Medium

• 155. Min Stack
  Difficulty: Medium

• 1582. Design Browser History
  Difficulty: Medium

• 1720. Crawler Log Folder
  Difficulty: Easy

• 1918. Maximum Score of a Good Subarray
  Difficulty: Hard

• 20. Valid Parentheses
  Difficulty: Easy

• 225. Implement Stack using Queues
  Difficulty: Easy

• 227. Basic Calculator II
  Difficulty: Medium

• 232. Implement Queue using Stacks
  Difficulty: Easy

• 234. Palindrome Linked List
  Difficulty: Easy

• 2470. Removing Stars From a String
  Difficulty: Medium

• 2871. Double a Number Represented as a Linked List
  Difficulty: Medium

• 316. Remove Duplicate Letters
  Difficulty: Medium

• 402. Remove K Digits
  Difficulty: Medium

• 42. Trapping Rain Water
  Difficulty: Hard

• 496. Next Greater Element I
  Difficulty: Easy

• 503. Next Greater Element II
  Difficulty: Medium

• 682. Baseball Game
  Difficulty: Easy

• 735. Asteroid Collision
  Difficulty: Medium

• 739. Daily Temperatures
  Difficulty: Medium

• 775. N-ary Tree Preorder Traversal
  Difficulty: Easy

• 776. N-ary Tree Postorder Traversal
  Difficulty: Easy

• 84. Largest Rectangle in Histogram
  Difficulty: Hard

• 874. Backspace String Compare
  Difficulty: Easy

• 883. Car Fleet
  Difficulty: Medium

• 937. Online Stock Span
  Difficulty: Medium

• 94. Binary Tree Inorder Traversal
  Difficulty: Easy

String (Total: 89)

• 1044. Find Common Characters
  Difficulty: Easy

• 1128. Remove All Adjacent Duplicates In String
  Difficulty: Easy

• 1159. Smallest Subsequence of Distinct Characters
  Difficulty: Medium

• 12. Integer to Roman
  Difficulty: Medium

• 125. Valid Palindrome
  Difficulty: Easy

• 13. Roman to Integer
  Difficulty: Easy

• 1320. Remove All Adjacent Duplicates in String II
  Difficulty: Medium

• 1321. Get Equal Substrings Within Budget
  Difficulty: Medium

• 1351. Replace the Substring for Balanced String
  Difficulty: Medium

• 1353. Find Resultant Array After Removing Anagrams
  Difficulty: Easy

• 14. Longest Common Prefix
  Difficulty: Easy

• 1567. Maximum Number of Vowels in a Substring of Given Length
  Difficulty: Medium

• 168. Excel Sheet Column Title
  Difficulty: Easy

• 17. Letter Combinations of a Phone Number
  Difficulty: Medium

• 171. Excel Sheet Column Number
  Difficulty: Easy

• 1720. Crawler Log Folder
  Difficulty: Easy

• 1781. Check If Two String Arrays are Equivalent
  Difficulty: Easy

• 187. Repeated DNA Sequences
  Difficulty: Medium

• 1873. Longest Nice Substring
  Difficulty: Easy

• 1894. Merge Strings Alternately
  Difficulty: Easy

• 1970. Sorting the Sentence
  Difficulty: Easy

• 20. Valid Parentheses
  Difficulty: Easy

• 2010. Check if Word Equals Summation of Two Words
  Difficulty: Easy

• 205. Isomorphic Strings
  Difficulty: Easy

• 208. Implement Trie (Prefix Tree)
  Difficulty: Medium

• 2134. Maximize the Confusion of an Exam
  Difficulty: Medium

• 2137. Final Value of Variable After Performing Operations
  Difficulty: Easy

• 22. Generate Parentheses
  Difficulty: Medium

• 227. Basic Calculator II
  Difficulty: Medium

• 2377. Check if Number Has Equal Digit Count and Digit Value
  Difficulty: Easy

• 242. Valid Anagram
  Difficulty: Easy

• 2429. Design a Food Rating System
  Difficulty: Medium

• 2465. Shifting Letters II
  Difficulty: Medium

• 2470. Removing Stars From a String
  Difficulty: Medium

• 2532. Remove Letter To Equalize Frequency
  Difficulty: Easy

• 257. Binary Tree Paths
  Difficulty: Easy

• 2580. Circular Sentence
  Difficulty: Easy

• 2599. Take K of Each Character From Left and Right
  Difficulty: Medium

• 28. Find the Index of the First Occurrence in a String
  Difficulty: Easy

• 290. Word Pattern
  Difficulty: Easy

• 299. Bulls and Cows
  Difficulty: Medium

• 3. Longest Substring Without Repeating Characters
  Difficulty: Medium

• 30. Substring with Concatenation of All Words
  Difficulty: Hard

• 316. Remove Duplicate Letters
  Difficulty: Medium

• 3379. Score of a String
  Difficulty: Easy

• 344. Reverse String
  Difficulty: Easy

• 345. Reverse Vowels of a String
  Difficulty: Easy

• 3533. Snake in Matrix
  Difficulty: Easy

• 3736. Find Valid Pair of Adjacent Digits in String
  Difficulty: Easy

• 3753. Maximum Difference Between Even and Odd Frequency I
  Difficulty: Easy

• 3811. Reverse Degree of a String
  Difficulty: Easy

• 383. Ransom Note
  Difficulty: Easy

• 387. First Unique Character in a String
  Difficulty: Easy

• 3871. Minimum Deletions for At Most K Distinct Characters
  Difficulty: Easy

• 3872. Find Most Frequent Vowel and Consonant
  Difficulty: Easy

• 389. Find the Difference
  Difficulty: Easy

• 392. Is Subsequence
  Difficulty: Easy

• 402. Remove K Digits
  Difficulty: Medium

• 405. Convert a Number to Hexadecimal
  Difficulty: Easy

• 409. Longest Palindrome
  Difficulty: Easy

• 412. Fizz Buzz
  Difficulty: Easy

• 415. Add Strings
  Difficulty: Easy

• 424. Longest Repeating Character Replacement
  Difficulty: Medium

• 43. Multiply Strings
  Difficulty: Medium

• 434. Number of Segments in a String
  Difficulty: Easy

• 438. Find All Anagrams in a String
  Difficulty: Medium

• 459. Repeated Substring Pattern
  Difficulty: Easy

• 482. License Key Formatting
  Difficulty: Easy

• 49. Group Anagrams
  Difficulty: Medium

• 5. Longest Palindromic Substring
  Difficulty: Medium

• 500. Keyboard Row
  Difficulty: Easy

• 541. Reverse String II
  Difficulty: Easy

• 557. Reverse Words in a String III
  Difficulty: Easy

• 567. Permutation in String
  Difficulty: Medium

• 58. Length of Last Word
  Difficulty: Easy

• 599. Minimum Index Sum of Two Lists
  Difficulty: Easy

• 6. Zigzag Conversion
  Difficulty: Medium

• 67. Add Binary
  Difficulty: Easy

• 686. Repeated String Match
  Difficulty: Medium

• 742. To Lower Case
  Difficulty: Easy

• 76. Minimum Window Substring
  Difficulty: Hard

• 768. Partition Labels
  Difficulty: Medium

• 782. Jewels and Stones
  Difficulty: Easy

• 79. Word Search
  Difficulty: Medium

• 812. Rotate String
  Difficulty: Easy

• 822. Unique Morse Code Words
  Difficulty: Easy

• 841. Shortest Distance to a Character
  Difficulty: Easy

• 874. Backspace String Compare
  Difficulty: Easy

• 961. Long Pressed Name
  Difficulty: Easy

String Matching (Total: 5)

• 28. Find the Index of the First Occurrence in a String
  Difficulty: Easy

• 459. Repeated Substring Pattern
  Difficulty: Easy

• 572. Subtree of Another Tree
  Difficulty: Easy

• 686. Repeated String Match
  Difficulty: Medium

• 812. Rotate String
  Difficulty: Easy

Tree (Total: 36)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 100. Same Tree
  Difficulty: Easy

• 101. Symmetric Tree
  Difficulty: Easy

• 102. Binary Tree Level Order Traversal
  Difficulty: Medium

• 1035. Cousins in Binary Tree
  Difficulty: Easy

• 104. Maximum Depth of Binary Tree
  Difficulty: Easy

• 105. Construct Binary Tree from Preorder and Inorder Traversal
  Difficulty: Medium

• 108. Convert Sorted Array to Binary Search Tree
  Difficulty: Easy

• 110. Balanced Binary Tree
  Difficulty: Easy

• 111. Minimum Depth of Binary Tree
  Difficulty: Easy

• 112. Path Sum
  Difficulty: Easy

• 1254. Deepest Leaves Sum
  Difficulty: Medium

• 144. Binary Tree Preorder Traversal
  Difficulty: Easy

• 145. Binary Tree Postorder Traversal
  Difficulty: Easy

• 222. Count Complete Tree Nodes
  Difficulty: Easy

• 226. Invert Binary Tree
  Difficulty: Easy

• 2416. Evaluate Boolean Binary Tree
  Difficulty: Easy

• 257. Binary Tree Paths
  Difficulty: Easy

• 404. Sum of Left Leaves
  Difficulty: Easy

• 450. Delete Node in a BST
  Difficulty: Medium

• 501. Find Mode in Binary Search Tree
  Difficulty: Easy

• 513. Find Bottom Left Tree Value
  Difficulty: Medium

• 543. Diameter of Binary Tree
  Difficulty: Easy

• 563. Binary Tree Tilt
  Difficulty: Easy

• 572. Subtree of Another Tree
  Difficulty: Easy

• 617. Merge Two Binary Trees
  Difficulty: Easy

• 637. Average of Levels in Binary Tree
  Difficulty: Easy

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 774. Maximum Depth of N-ary Tree
  Difficulty: Easy

• 775. N-ary Tree Preorder Traversal
  Difficulty: Easy

• 776. N-ary Tree Postorder Traversal
  Difficulty: Easy

• 783. Search in a Binary Search Tree
  Difficulty: Easy

• 789. Kth Largest Element in a Stream
  Difficulty: Easy

• 94. Binary Tree Inorder Traversal
  Difficulty: Easy

• 975. Range Sum of BST
  Difficulty: Easy

• 98. Validate Binary Search Tree
  Difficulty: Medium

Trie (Total: 3)

• 14. Longest Common Prefix
  Difficulty: Easy

• 208. Implement Trie (Prefix Tree)
  Difficulty: Medium

• 386. Lexicographical Numbers
  Difficulty: Medium

Two Pointers (Total: 60)

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 1019. Squares of a Sorted Array
  Difficulty: Easy

• 1028. Interval List Intersections
  Difficulty: Medium

• 11. Container With Most Water
  Difficulty: Medium

• 125. Valid Palindrome
  Difficulty: Easy

• 141. Linked List Cycle
  Difficulty: Easy

• 142. Linked List Cycle II
  Difficulty: Medium

• 143. Reorder List
  Difficulty: Medium

• 1468. Check If N and Its Double Exist
  Difficulty: Easy

• 148. Sort List
  Difficulty: Medium

• 15. 3Sum
  Difficulty: Medium

• 16. 3Sum Closest
  Difficulty: Medium

• 160. Intersection of Two Linked Lists
  Difficulty: Easy

• 1615. Range Sum of Sorted Subarray Sums
  Difficulty: Medium

• 167. Two Sum II - Input Array Is Sorted
  Difficulty: Medium

• 18. 4Sum
  Difficulty: Medium

• 189. Rotate Array
  Difficulty: Medium

• 1894. Merge Strings Alternately
  Difficulty: Easy

• 19. Remove Nth Node From End of List
  Difficulty: Medium

• 1918. Maximum Score of a Good Subarray
  Difficulty: Hard

• 202. Happy Number
  Difficulty: Easy

• 2265. Partition Array According to Given Pivot
  Difficulty: Medium

• 2320. Find All K-Distant Indices in an Array
  Difficulty: Easy

• 234. Palindrome Linked List
  Difficulty: Easy

• 2551. Apply Operations to an Array
  Difficulty: Easy

• 2581. Divide Players Into Teams of Equal Skill
  Difficulty: Medium

• 26. Remove Duplicates from Sorted Array
  Difficulty: Easy

• 2634. Minimum Common Value
  Difficulty: Easy

• 27. Remove Element
  Difficulty: Easy

• 28. Find the Index of the First Occurrence in a String
  Difficulty: Easy

• 283. Move Zeroes
  Difficulty: Easy

• 31. Next Permutation
  Difficulty: Medium

• 344. Reverse String
  Difficulty: Easy

• 345. Reverse Vowels of a String
  Difficulty: Easy

• 349. Intersection of Two Arrays
  Difficulty: Easy

• 350. Intersection of Two Arrays II
  Difficulty: Easy

• 392. Is Subsequence
  Difficulty: Easy

• 3973. Flip Square Submatrix Vertically
  Difficulty: Easy

• 42. Trapping Rain Water
  Difficulty: Hard

• 455. Assign Cookies
  Difficulty: Easy

• 5. Longest Palindromic Substring
  Difficulty: Medium

• 528. Swapping Nodes in a Linked List
  Difficulty: Medium

• 541. Reverse String II
  Difficulty: Easy

• 557. Reverse Words in a String III
  Difficulty: Easy

• 567. Permutation in String
  Difficulty: Medium

• 61. Rotate List
  Difficulty: Medium

• 633. Sum of Square Numbers
  Difficulty: Medium

• 653. Two Sum IV - Input is a BST
  Difficulty: Easy

• 658. Find K Closest Elements
  Difficulty: Medium

• 75. Sort Colors
  Difficulty: Medium

• 768. Partition Labels
  Difficulty: Medium

• 841. Shortest Distance to a Character
  Difficulty: Easy

• 861. Flipping an Image
  Difficulty: Easy

• 874. Backspace String Compare
  Difficulty: Easy

• 88. Merge Sorted Array
  Difficulty: Easy

• 908. Middle of the Linked List
  Difficulty: Easy

• 917. Boats to Save People
  Difficulty: Medium

• 941. Sort Array By Parity
  Difficulty: Easy

• 958. Sort Array By Parity II
  Difficulty: Easy

• 961. Long Pressed Name
  Difficulty: Easy

Union Find (Total: 6)

• 128. Longest Consecutive Sequence
  Difficulty: Medium

• 130. Surrounded Regions
  Difficulty: Medium

• 1380. Number of Closed Islands
  Difficulty: Medium

• 200. Number of Islands
  Difficulty: Medium

• 2121. Find if Path Exists in Graph
  Difficulty: Easy

• 695. Max Area of Island
  Difficulty: Medium

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