| total | easy | medium | hard |
|---|---|---|---|
| 300 | 110 | 153 | 37 |
- Two Sum
- Add Two Numbers
- Longest Substring Without Repeating Characters
- Median of Two Sorted Arrays
- Longest Palindromic Substring
- ZigZag Conversion
- Reverse Integer
- String to Integer (atoi)
- Palindrome Number
- Regular Expression Matching
- Container With Most Water
- Integer to Roman
- Roman to Integer
- Longest Common Prefix
- 3Sum
- 3Sum Closest
- Letter Combinations of a Phone Number
- 4Sum
- Remove Nth Node From End of List
- Valid Parentheses
- Merge Two Sorted Lists
- Generate Parentheses
- Merge k Sorted Lists
- Swap Nodes in Pairs
- Reverse Nodes in k-Group
- Remove Duplicates from Sorted Array
- Remove Element
- Implement strStr()
- Divide Two Integers
- Substring with Concatenation of All Words
- Next Permutation
- Longest Valid Parentheses
- Search in Rotated Sorted Array
- Find First and Last Position of Element in Sorted Array
- Search Insert Position
- Valid Sudoku
- Sudoku Solver
- Count and Say
- Combination Sum
- Combination Sum II
- First Missing Positive
- Trapping Rain Water
- Multiply Strings
- Wildcard Matching
- Jump Game II
- Permutations
- Permutations II
- Rotate Image
- Group Anagrams
- Pow(x, n)
- N-Queens
- N-Queens II
- Maximum Subarray
- Spiral Matrix
- Jump Game
- Merge Intervals
- Insert Interval
- Length of Last Word
- Spiral Matrix II
- Permutation Sequence
- Rotate List
- Unique Paths
- Unique Paths II
- Minimum Path Sum
- Plus One
- Add Binary
- Sqrt(x)
- Climbing Stairs
- Simplify Path
- Edit Distance
- Set Matrix Zeroes
- Search a 2D Matrix
- Sort Colors
- Minimum Window Substring
- Combinations
- Subsets
- Word Search
- Remove Duplicates from Sorted Array II
- Search in Rotated Sorted Array II
- Remove Duplicates from Sorted List II
- Remove Duplicates from Sorted List
- Largest Rectangle in Histogram
- Maximal Rectangle
- Partition List
- Merge Sorted Array
- Gray Code
- Subsets II
- Decode Ways
- Reverse Linked List II
- Restore IP Addresses
- Binary Tree Inorder Traversal
- Unique Binary Search Trees II
- Unique Binary Search Trees
- Interleaving String
- Validate Binary Search Tree
- Recover Binary Search Tree
- Same Tree
- Symmetric Tree
- Binary Tree Level Order Traversal
- Binary Tree Zigzag Level Order Traversal
- Maximum Depth of Binary Tree
- Construct Binary Tree from Preorder and Inorder Traversal
- Construct Binary Tree from Inorder and Postorder Traversal
- Binary Tree Level Order Traversal II
- Convert Sorted Array to Binary Search Tree
- Convert Sorted List to Binary Search Tree
- Balanced Binary Tree
- Minimum Depth of Binary Tree
- Path Sum
- Path Sum II
- Flatten Binary Tree to Linked List
- Distinct Subsequences
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node II
- Pascal's Triangle
- Pascal's Triangle II
- Triangle
- Best Time to Buy and Sell Stock
- Best Time to Buy and Sell Stock II
- Best Time to Buy and Sell Stock III
- Binary Tree Maximum Path Sum
- Valid Palindrome
- Word Ladder II
- Word Ladder
- Longest Consecutive Sequence
- Sum Root to Leaf Numbers
- Surrounded Regions
- Palindrome Partitioning
- Palindrome Partitioning II
- Candy
- Single Number
- Single Number II
- Copy List with Random Pointer
- Word Break
- Word Break II
- Linked List Cycle
- Linked List Cycle II
- Reorder List
- Binary Tree Preorder Traversal
- Binary Tree Postorder Traversal
- LRU Cache
- Insertion Sort List
- Sort List
- Max Points on a Line
- Evaluate Reverse Polish Notation
- Reverse Words in a String
- Maximum Product Subarray
- Find Minimum in Rotated Sorted Array
- Find Minimum in Rotated Sorted Array II
- Min Stack
- Intersection of Two Linked Lists
- Find Peak Element
- Two Sum II - Input array is sorted
- Excel Sheet Column Title
- Majority Element
- Excel Sheet Column Number
- Factorial Trailing Zeroes
- Binary Search Tree Iterator
- Combine Two Tables
- Second Highest Salary
- Largest Number
- Employees Earning More Than Their Managers
- Duplicate Emails
- Customers Who Never Order
- Best Time to Buy and Sell Stock IV
- Rotate Array
- Reverse Bits
- Number of 1 Bits
- Rising Temperature
- Delete Duplicate Emails
- Rising Temperature
- House Robber
- Binary Tree Right Side View
- Number of Islands
- Bitwise AND of Numbers Range
- Happy Number
- Remove Linked List Elements
- Count Primes
- Reverse Linked List
- Course Schedule
- Implement Trie (Prefix Tree)
- Course Schedule II
- Add and Search Word - Data structure design
- House Robber II
- Kth Largest Element in an Array
- Combination Sum III
- Maximal Square
- Count Complete Tree Nodes
- Implement Stack using Queues
- Kth Smallest Element in a BST
- Power of Two
- Implement Queue using Stacks
- Number of Digit One
- Palindrome Linked List
- Lowest Common Ancestor of a Binary Tree
- Delete Node in a Linked List
- Sliding Window Maximum
- Search a 2D Matrix II
- Binary Tree Paths
- Single Number III
- Ugly Number
- Ugly Number II
- Move Zeroes
- Serialize and Deserialize Binary Tree
- Longest Increasing Subsequence
- Range Sum Query - Mutable
- Best Time to Buy and Sell Stock with Cooldown
- Minimum Height Trees
- Coin Change
- Odd Even Linked List
- Longest Increasing Path in a Matrix
- House Robber III
- Reverse String
- Top K Frequent Elements
- Combination Sum IV
- Shuffle an Array
- First Unique Character in a String
- Find the Difference
- Is Subsequence
- Decode String
- Longest Substring with At Least K Repeating Characters
- Sum of Left Leaves
- Third Maximum Number
- Add Strings
- Maximum XOR of Two Numbers in an Array
- N-ary Tree Level Order Traversal
- Path Sum III
- Arranging Coins
- Find All Duplicates in an Array
- Add Two Numbers II
- Find All Numbers Disappeared in an Array
- Sort Characters By Frequency
- Can I Win
- Unique Substrings in Wraparound String
- Implement Rand10() Using Rand7()
- Heaters
- Increasing Subsequences
- Target Sum
- Next Greater Element I
- Keyboard Row
- Fibonacci Number
- Find Bottom Left Tree Value
- Random Pick with Weight
- 01 Matrix
- Diameter of Binary Tree
- Friend Circles
- Maximum Depth of N-ary Tree
- N-ary Tree Preorder Traversal
- N-ary Tree Postorder Traversal
- Big Countries
- Classes More Than 5 Students
- Not Boring Movies
- Design Circular Queue
- Swap Salary
- Maximum Product of Three Numbers
- Sum of Square Numbers
- Average of Levels in Binary Tree
- Redundant Connection
- Longest Continuous Increasing Subsequence
- Top K Frequent Words
- Degree of an Array
- Search in a Binary Search Tree
- Kth Largest Element in a Stream
- Design HashSet
- Design HashMap
- Design Linked List
- Best Time to Buy and Sell Stock with Transaction Fee
- Maximum Length of Repeated Subarray
- Longest Word in Dictionary
- Find Pivot Index
- Daily Temperatures
- Min Cost Climbing Stairs
- Open the Lock
- Reach a Number
- Reorganize String
- Is Graph Bipartite?
- Number of Matching Subsequences
- Rotate String
- Find Eventual Safe States
- Number of Lines To Write String
- Consecutive Numbers Sum
- Shifting Letters
- Peak Index in a Mountain Array
- Leaf-Similar Trees
- Length of Longest Fibonacci Subsequence
- Construct Binary Tree from Preorder and Postorder Traversal
- Bitwise ORs of Subarrays
- Sum of Subarray Minimums
- Word Subsets
- Range Sum of BST
- Delete Columns to Make Sorted
- Bag of Tokens
- K Closest Points to Origin
- Squares of a Sorted Array
- Smallest String Starting From Leaf
- Broken Calculator
- Rotting Oranges
- Binary Search Tree to Greater Sum Tree
- Longest String Chain
- Letter Tile Possibilities