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Previous Year Questions
Remove Invalid Parentheses
Hard
Integer to English Words
Hard
Verifying an Alien Dictionary
Easy
Read N Characters Given Read4 II - Call multiple times
Hard
Serialize and Deserialize Binary Tree
Hard
Regular Expression Matching
Hard
Decode Ways
Medium
Meeting Rooms II
Medium
Product of Array Except Self
Medium
Valid Palindrome II
Easy
3Sum
Medium
Subarray Sum Equals K
Medium
First Bad Version
Easy
Minimum Window Substring
Hard
K Closest Points to Origin
Medium
Add Binary
Easy
Merge k Sorted Lists
Hard
Move Zeroes
Easy
Minimum Remove to Make Valid Parentheses
Medium
Valid Palindrome
Easy
Divide Two Integers
Medium
Next Permutation
Medium
Binary Search Tree Iterator
Medium
Expression Add Operators
Hard
Add and Search Word - Data structure design
Medium
Valid Number
Hard
Read N Characters Given Read4
Easy
Binary Tree Maximum Path Sum
Hard
Binary Tree Vertical Order Traversal
Medium
Letter Combinations of a Phone Number
Medium
Merge Intervals
Medium
Convert Binary Search Tree to Sorted Doubly Linked List
Medium
Alien Dictionary
Hard
Two Sum
Easy
Clone Graph
Medium
Maximum Size Subarray Sum Equals k
Medium
Find All Anagrams in a String
Medium
Sparse Matrix Multiplication
Medium
Add Strings
Easy
Number of Islands
Medium
Palindrome Pairs
Hard
Kth Largest Element in an Array
Medium
Diameter of Binary Tree
Easy
Binary Tree Paths
Easy
Continuous Subarray Sum
Medium
Find the Celebrity
Medium
Task Scheduler
Medium
Multiply Strings
Medium
Validate Binary Search Tree
Medium
Trapping Rain Water
Hard
Maximum Sum of 3 Non-Overlapping Subarrays
Hard
Intersection of Two Arrays
Easy
Longest Substring with At Most K Distinct Characters
Hard
Best Time to Buy and Sell Stock
Easy
Merge Sorted Array
Easy
Flatten Binary Tree to Linked List
Medium
Copy List with Random Pointer
Medium
Exclusive Time of Functions
Medium
Accounts Merge
Medium
One Edit Distance
Medium
LRU Cache
Medium
Range Sum Query 2D - Immutable
Medium
Binary Tree Right Side View
Medium
Word Break
Medium
Is Graph Bipartite?
Medium
Search in Rotated Sorted Array
Medium
Shortest Distance from All Buildings
Hard
Reorder List
Medium
Simplify Path
Medium
Lowest Common Ancestor of a Binary Tree
Medium
Walls and Gates
Medium
Interval List Intersections
Medium
Find First and Last Position of Element in Sorted Array
Medium
Flatten Nested List Iterator
Medium
Monotonic Array
Easy
Random Pick Index
Medium
Valid Parentheses
Easy
Basic Calculator II
Medium
Insert Interval
Hard
Closest Binary Search Tree Value
Easy
Intersection of Two Arrays II
Easy
Sort Transformed Array
Medium
Friends Of Appropriate Ages
Medium
Rearrange String k Distance Apart
Hard
Longest Valid Parentheses
Hard
Subsets
Medium
Strobogrammatic Number II
Medium
Design Tic-Tac-Toe
Medium
Insert into a Sorted Circular Linked List
Medium
Nested List Weight Sum
Easy
N-Queens
Hard
Goat Latin
Easy
Longest Increasing Subsequence
Medium
Strobogrammatic Number
Easy
Sort Colors
Medium
Maximum Swap
Medium
Check Completeness of a Binary Tree
Medium
Insert Delete GetRandom O(1)
Medium
Inorder Successor in BST
Medium
Island Perimeter
Easy
Range Sum of BST
Easy
Vertical Order Traversal of a Binary Tree
Medium
Basic Calculator
Hard
Word Ladder II
Hard
Convert Sorted List to Binary Search Tree
Medium
Random Pick with Weight
Medium
Maximum Subarray
Easy
Find Peak Element
Medium
Serialize and Deserialize BST
Medium
Meeting Rooms
Easy
Longest Substring Without Repeating Characters
Medium
Diagonal Traverse
Medium
Friend Requests I: Overall Acceptance Rate
Easy
Roman to Integer
Easy
Flatten 2D Vector
Medium
Longest Palindromic Substring
Medium
Word Ladder
Medium
Leftmost Column with at Least a One
Medium
Custom Sort String
Medium
Battleships in a Board
Medium
Target Sum
Medium
Sliding Window Maximum
Hard
Basic Calculator III
Hard
String to Integer (atoi)
Medium
Number of Islands II
Hard
Add Two Numbers
Medium
Reorganize String
Medium
Smallest Range Covering Elements from K Lists
Hard
Insert Delete GetRandom O(1) - Duplicates allowed
Hard
Reverse Linked List
Easy
Friend Requests II: Who Has the Most Friends
Medium
UTF-8 Validation
Medium
Wildcard Matching
Hard
Group Shifted Strings
Medium
Range Sum Query 2D - Mutable
Hard
Permutation in String
Medium
Permutations
Medium
Group Anagrams
Medium
Minimum Add to Make Parentheses Valid
Medium
Decode String
Medium
The Skyline Problem
Hard
Find K Closest Elements
Medium
All O`one Data Structure
Hard
Total Hamming Distance
Medium
Palindromic Substrings
Medium
Valid Word Abbreviation
Easy
Median of Two Sorted Arrays
Hard
Validate IP Address
Medium
Construct Binary Tree from Preorder and Inorder Traversal
Medium
Count and Say
Easy
Merge Two Sorted Lists
Easy
Kth Smallest Element in a BST
Medium
Valid Parenthesis String
Medium
Pow(x;n)
Medium
Moving Average from Data Stream
Easy
Missing Element in Sorted Array
Medium
Word Break II
Hard
Longest Arithmetic Sequence
Medium
Generate Parentheses
Medium
Longest Consecutive Sequence
Hard
Design Circular Queue
Medium
Kth Smallest Element in a Sorted Matrix
Medium
Combination Sum
Medium
Partition Equal Subset Sum
Medium
All Nodes Distance K in Binary Tree
Medium
Minimum Depth of Binary Tree
Easy
Minimum Knight Moves
Medium
Longest Continuous Increasing Subsequence
Easy
Reverse Nodes in k-Group
Hard
Implement Trie (Prefix Tree)
Medium
Binary Tree Level Order Traversal
Medium
Max Consecutive Ones III
Medium
Robot Room Cleaner
Hard
Restore IP Addresses
Medium
Word Search II
Hard
4Sum
Medium
Find Median from Data Stream
Hard
Palindrome Permutation
Easy
Reconstruct Itinerary
Medium
Construct Binary Tree from String
Medium
Word Frequency
Medium
Longest Increasing Path in a Matrix
Hard
Word Search
Medium
Minimum Size Subarray Sum
Medium
Toeplitz Matrix
Easy
Smallest Subtree with all the Deepest Nodes
Medium
Increasing Triplet Subsequence
Medium
Design Search Autocomplete System
Hard
The Maze
Medium
Bulb Switcher
Medium
Minimum Number of Arrows to Burst Balloons
Medium
Populating Next Right Pointers in Each Node II
Medium
Best Time to Buy and Sell Stock III
Hard
Frog Jump
Hard
Best Time to Buy and Sell Stock II
Easy
Search a 2D Matrix II
Medium
Lowest Common Ancestor of Deepest Leaves
Medium
Implement strStr()
Easy
Minesweeper
Medium
Top K Frequent Elements
Medium
Top K Frequent Words
Medium
Spiral Matrix III
Medium
Max Area of Island
Medium
Evaluate Division
Medium
Set Matrix Zeroes
Medium
Reverse Linked List II
Medium
Populating Next Right Pointers in Each Node
Medium
Maximum Vacation Days
Hard
Sliding Window Median
Hard
Course Schedule
Medium
Unique Paths
Medium
Search in Rotated Sorted Array II
Medium
Fraction to Recurring Decimal
Medium
Single Element in a Sorted Array
Medium
Split Array with Equal Sum
Medium
Spiral Matrix
Medium
Add Bold Tag in String
Medium
Number of Distinct Islands
Medium
Container With Most Water
Medium
Stickers to Spell Word
Hard
Lowest Common Ancestor of a Binary Search Tree
Easy
Substring with Concatenation of All Words
Hard
Nth Digit
Medium
Serialize and Deserialize N-ary Tree
Hard
Largest BST Subtree
Medium
Shortest Bridge
Medium
Backspace String Compare
Easy
Swap Nodes in Pairs
Medium
Recover Binary Search Tree
Hard
Binary Tree Longest Consecutive Sequence II
Medium
Maximum Difference Between Node and Ancestor
Medium
Best Meeting Point
Hard
Reported Posts
Easy
Subsets II
Medium
Knight Dialer
Medium
Text Justification
Hard
Binary Tree Longest Consecutive Sequence
Medium
Nested List Weight Sum II
Medium
Search a 2D Matrix
Medium
Wiggle Sort
Medium
Maximal Rectangle
Hard
Brick Wall
Medium
Edit Distance
Hard
Sudoku Solver
Hard
Missing Ranges
Medium
First Unique Character in a String
Easy
Sum Root to Leaf Numbers
Medium
Binary Tree Postorder Traversal
Hard
Valid Palindrome III
Hard
Squares of a Sorted Array
Easy
Sort List
Medium
Convert a Number to Hexadecimal
Easy
Decode Ways II
Hard
Sqrt(x)
Easy
Binary Tree Inorder Traversal
Medium
Largest Rectangle in Histogram
Hard
Minimum Area Rectangle
Medium
Closest Binary Search Tree Value II
Hard
Similar String Groups
Hard
Minimum Area Rectangle II
Medium
Second Degree Follower
Medium
Remove Duplicates from Sorted Array
Easy
Flatten a Multilevel Doubly Linked List
Medium
Longest Substring with At Least K Repeating Characters
Medium
Word Pattern II
Hard
Car Pooling
Medium
Number of 1 Bits
Easy
Coin Change
Medium
Next Greater Element III
Medium
Number of Connected Components in an Undirected Graph
Medium
Max Sum of Rectangle No Larger Than K
Hard
Valid Anagram
Easy
First Missing Positive
Hard
Add Two Numbers II
Medium
Find Pivot Index
Easy
Number of Ways to Stay in the Same Place After Some Steps
Hard
Maximum Product Subarray
Medium
Coin Change 2
Medium
Single Number II
Medium
Pancake Sorting
Medium
Valid Sudoku
Medium
Intersection of Two Linked Lists
Easy
Average of Levels in Binary Tree
Easy
Koko Eating Bananas
Medium
Remove Nth Node From End of List
Medium
Closest Leaf in a Binary Tree
Medium
Shortest Palindrome
Hard
Permutations II
Medium
Jump Game II
Hard
Strobogrammatic Number III
Hard
Jump Game
Medium
Web Crawler Multithreaded
Medium
Peeking Iterator
Medium
Remove Duplicate Letters
Hard
Symmetric Tree
Easy
Integer to Roman
Medium
Combination Sum II
Medium
Longest Absolute File Path
Medium
Data Stream as Disjoint Intervals
Hard
Longest Common Prefix
Easy
User Activity for the Past 30 Days II
Easy
Plus One
Easy
String Compression
Easy
Reported Posts II
Medium
Find Minimum in Rotated Sorted Array
Medium
Find Largest Value in Each Tree Row
Medium
Intersection of Three Sorted Arrays
Easy
Rectangle Area
Medium
Construct Binary Search Tree from Preorder Traversal
Medium
Unique Paths II
Medium
Convert Sorted Array to Binary Search Tree
Easy
Find the Closest Palindrome
Hard
Increasing Subsequences
Medium
Rotate Array
Easy
Combinations
Medium
Remove Sub-Folders from the Filesystem
Medium
Path Sum III
Medium
Is Subsequence
Easy
Rotate Image
Medium
Reverse Words in a String
Medium
Split BST
Medium
Page Recommendations
Medium
Knight Probability in Chessboard
Medium
Diagonal Traverse II
Medium
Single Number
Easy
Reverse Integer
Easy
Two Sum II - Input array is sorted
Easy
Friend Circles
Medium
Trapping Rain Water II
Hard
Evaluate Reverse Polish Notation
Medium
Stream of Characters
Hard
Reverse Vowels of a String
Easy
Kth Largest Element in a Stream
Easy
Find All Duplicates in an Array
Medium
Shortest Subarray with Sum at Least K
Hard
Exam Room
Medium
Range Sum Query - Immutable
Easy
Non-overlapping Intervals
Medium
Balanced Binary Tree
Easy
Shortest Path in Binary Matrix
Medium
Summary Ranges
Medium
Making A Large Island
Hard
Valid Tic-Tac-Toe State
Medium
Shuffle an Array
Medium
Peak Index in a Mountain Array
Easy
Maximum Sum Circular Subarray
Medium
3Sum Closest
Medium
Maximum Depth of Binary Tree
Easy
Repeated String Match
Easy
Generate Random Point in a Circle
Medium
Wiggle Sort II
Medium
Path Sum
Easy
Tree Diameter
Medium
Stamping The Sequence
Hard
Design Circular Deque
Medium
Min Stack
Easy
Excel Sheet Column Number
Easy
Combination Sum IV
Medium
Permutation Sequence
Hard
Maximum Width of Binary Tree
Medium
Linked List Random Node
Medium
Count Different Palindromic Subsequences
Hard
Third Maximum Number
Easy
Employee Free Time
Hard
Minimum Cost For Tickets
Medium
Delete Node in a BST
Medium
Course Schedule II
Medium
The Maze II
Medium
Equal Tree Partition
Medium
Palindrome Linked List
Easy
Arithmetic Slices II - Subsequence
Hard
Find Duplicate File in System
Medium
Excel Sheet Column Title
Easy
Range Sum Query - Mutable
Medium
Max Stack
Easy
Best Time to Buy and Sell Stock IV
Hard
Print Binary Tree
Medium
Reverse String
Easy
Maximum Binary Tree
Medium
Maximal Square
Medium
Longest Substring with At Most Two Distinct Characters
Medium
Different Ways to Add Parentheses
Medium
Number Of Corner Rectangles
Medium
Longest Palindromic Subsequence
Medium
Pacific Atlantic Water Flow
Medium
Trim a Binary Search Tree
Easy
Split Array Largest Sum
Hard
Graph Valid Tree
Medium
ZigZag Conversion
Medium
Next Greater Element II
Medium
Burst Balloons
Hard
Previous Permutation With One Swap
Medium
Count of Smaller Numbers After Self
Hard
Uncommon Words from Two Sentences
Easy
Word Pattern
Easy
Sum of Two Integers
Medium
Open the Lock
Medium
Get Highest Answer Rate Question
Medium
Best Time to Buy and Sell Stock with Transaction Fee
Medium
Possible Bipartition
Medium
Next Greater Element I
Easy
Rank Scores
Medium
Next Closest Time
Medium
Binary Tree Zigzag Level Order Traversal
Medium
Time Based Key-Value Store
Medium
Construct Binary Tree from Preorder and Postorder Traversal
Medium
Valid Square
Medium
Word Subsets
Medium
Palindrome Number
Easy
Surrounded Regions
Medium
Odd Even Linked List
Medium
Guess the Word
Hard
Arithmetic Slices
Medium
Encode and Decode TinyURL
Medium
Construct Binary Tree from Inorder and Postorder Traversal
Medium
Find K Pairs with Smallest Sums
Medium
Implement Magic Dictionary
Medium
Candy Crush
Medium
Path Sum II
Medium
Unique Binary Search Trees II
Medium
Factorial Trailing Zeroes
Easy
Second Highest Salary
Easy
Count Univalue Subtrees
Medium
Remove All Adjacent Duplicates in String II
Medium
Partition Array for Maximum Sum
Medium
Count Primes
Easy
Same Tree
Easy
Invert Binary Tree
Easy
H-Index
Medium
Counting Bits
Medium
Hamming Distance
Easy
Snapshot Array
Medium
Subtree of Another Tree
Easy
Count Complete Tree Nodes
Medium
Shifting Letters
Medium
Find the Kth Smallest Sum of a Matrix With Sorted Rows
Hard
Largest Number
Medium
Contiguous Array
Medium
Missing Number
Easy
Find Winner on a Tic Tac Toe Game
Easy
Rotate List
Medium
Remove All Adjacent Duplicates In String
Easy
Paint House II
Hard
Number of Matching Subsequences
Medium
Employees Earning More Than Their Managers
Easy
Perfect Squares
Medium
Vowel Spellchecker
Medium
Climbing Stairs
Easy
Sliding Puzzle
Hard
Pascal's Triangle
Easy
Find a Corresponding Node of a Binary Tree in a Clone of That Tree
Medium
Number of Ways to Paint N × 3 Grid
Hard
Remove K Digits
Medium
Linked List Cycle
Easy
Maximum Product of Three Numbers
Easy
User Activity for the Past 30 Days I
Easy
Spiral Matrix II
Medium
Shortest Distance to a Character
Easy
Longest Repeating Substring
Medium
Project Employees III
Medium
Number of Comments per Post
Easy
Find Duplicate Subtrees
Medium
Minimum Number of K Consecutive Bit Flips
Hard
Rotated Digits
Easy
Defanging an IP Address
Easy
Find the Duplicate Number
Medium
Next Greater Node In Linked List
Medium
Game Play Analysis IV
Medium
Maximum Width Ramp
Medium
Partition to K Equal Sum Subsets
Medium
Super Egg Drop
Hard
Number of Longest Increasing Subsequence
Medium
Check If Word Is Valid After Substitutions
Medium
Number of Closed Islands
Medium
Shortest Way to Form String
Medium
Swim in Rising Water
Hard
Majority Element II
Medium
Cheapest Flights Within K Stops
Medium
Element Appearing More Than 25% In Sorted Array
Easy
Campus Bikes
Medium
Game of Life
Medium
Find the Town Judge
Easy
Number of Atoms
Hard
Fibonacci Number
Easy
Concatenated Words
Hard
Design Snake Game
Medium
Apples & Oranges
Medium
Contains Duplicate
Easy
All Elements in Two Binary Search Trees
Medium
Distribute Coins in Binary Tree
Medium
Remove Duplicates from Sorted List
Easy
Two Sum IV - Input is a BST
Easy
Happy Number
Easy
Minimum Height Trees
Medium
24 Game
Hard
Remove Linked List Elements
Easy
Isomorphic Strings
Easy
Flood Fill
Easy
Number of Subsequences That Satisfy the Given Sum Condition
Medium
Valid Triangle Number
Medium
Path with Maximum Gold
Medium
Single Number III
Medium
Daily Temperatures
Medium
Queue Reconstruction by Height
Medium
Design HashMap
Easy
Leaf-Similar Trees
Easy
Cousins in Binary Tree
Easy
House Robber III
Medium
Sort Array By Parity
Easy
Maximum Sum of Two Non-Overlapping Subarrays
Medium
Maximum Length of Pair Chain
Medium
Wiggle Subsequence
Medium
Unique Binary Search Trees
Medium
Insert into a Binary Search Tree
Medium
Best Time to Buy and Sell Stock with Cooldown
Medium
Number of Days Between Two Dates
Easy
Find Minimum in Rotated Sorted Array II
Hard
Remove Duplicates from Sorted Array II
Medium
Flipping an Image
Easy
Can Place Flowers
Easy
Minimum Path Sum
Medium
N-th Tribonacci Number
Easy
Delete Node in a Linked List
Easy
Minimum Time Visiting All Points
Easy
Remove Outermost Parentheses
Easy
Jewels and Stones
Easy
Find N Unique Integers Sum up to Zero
Easy
Sum of Left Leaves
Easy
Sort Characters By Frequency
Medium
Longest Common Subsequence
Medium
Partition Labels
Medium
Shuffle String
Easy
H-Index II
Medium
Prefix and Suffix Search
Hard
Largest Plus Sign
Medium
Letter Case Permutation
Medium
Minimum Swaps To Make Sequences Increasing
Medium
Groups of Special-Equivalent Strings
Easy
Binary Tree Cameras
Hard
Add to Array-Form of Integer
Easy
Maximum Binary Tree II
Medium
Moving Stones Until Consecutive
Easy
Moving Stones Until Consecutive II
Medium
Project Employees I
Easy
Project Employees II
Easy
Validate Binary Tree Nodes
Medium
Queries Quality and Percentage
Easy
Report Contiguous Dates
Hard
Web Crawler
Medium
Ads Performance
Easy
Apply Discount Every n Orders
Medium
Customers Who Bought Products A and B but Not C
Medium
Minimum Time to Collect All Apples in a Tree
Medium
Make Two Arrays Equal by Reversing Sub-arrays
Easy
Maximum Number of Darts Inside of a Circular Dartboard
Hard
Diameter of N-Ary Tree
Medium
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