Easy
Array
Strings
Linked List
Trees
Sorting and Searching
Dynamic Programming
Design
Math
Fizz Buzz
Count Primes
Power of Three
Roman to Integer
Others
Number of 1 Bits
Hamming Distance
Reverse Bits
Pascal’s Triangle
Valid Parentheses
Missing Number
Medium
Array and Strings
3Sum
Set Matrix Zeroes
Group Anagrams
Longest Substring Without Repeating Characters
Longest Palindromic Substring
Increasing Triplet Subsequence
Missing Ranges
Count and Say
Linked List
Add Two Numbers
Odd Even Linked List
Intersection of Two Linked Lists
Trees and Graphs
Binary Tree Inorder Traversal
Binary Tree Zigzag Level Order Traversal
Construct Binary Tree from Preorder and Inorder Traversal
Populating Next Right Pointers in Each Node
Kth Smallest Element in a BST
Inorder Successor in BST
Number of Islands
Backtracking
Letter Combinations of a Phone Number
Generate Parentheses
Permutations
Subsets
Word Search
Sorting and Searching
Sort Colors
Top K Frequent Elements
Kth Largest Element in an Array
Find Peak Element
Search for a Range
Merge Intervals
Search in Rotated Sorted Array
Meeting Rooms II
Search a 2D Matrix II
Dynamic Programming
Jump Game
Unique Paths
Coin Change
Longest Increasing Subsequence
Design
Flatten 2D Vector
Serialize and Deserialize Binary Tree
Insert Delete GetRandom O(1)
Design Tic-Tac-Toe
Math
Happy Number
Factorial Trailing Zeroes
Excel Sheet Column Number
Pow(x, n)
Sqrt(x)
Divide Two Integers
Fraction to Recurring Decimal
Others
Sum of Two Integers
Evaluate Reverse Polish Notation
Majority Element
Find the Celebrity
Task Scheduler
Hard
Array and Strings
Product of Array Except Self
Spiral Matrix
4Sum II
Container With Most Water
Game of Life
First Missing Positive
Longest Consecutive Sequence
Find the Duplicate Number
Longest Substring with At Most K Distinct Characters
Basic Calculator II
Sliding Window Maximum
Minimum Window Substring
Linked List
Merge k Sorted Lists
Sort List
Copy List with Random Pointer
Trees and Graphs
Word Ladder
Surrounded Regions
Lowest Common Ancestor of a Binary Tree
Binary Tree Maximum Path Sum
Friend Circles
Course Schedule
Course Schedule II
Longest Increasing Path in a Matrix
Alien Dictionary
Count of Smaller Numbers After Self
Backtracking
Palindrome Partitioning
Word Search II
Remove Invalid Parentheses
Wildcard Matching
Regular Expression Matching
Sorting and Searching
Wiggle Sort II
Kth Smallest Element in a Sorted Matrix
Median of Two Sorted Arrays
Dynamic Programming
Maximum Product Subarray
Decode Ways
Best Time to Buy and Sell Stock with Cooldown
Perfect Squares
Word Break
Word Break II
Burst Balloons
Design
LRU Cache
Implement Trie (Prefix Tree)
Flatten Nested List Iterator
Find Median from Data Stream
Range Sum Query 2D – Mutable
Math
Largest Number
Max Points on a Line
Others
Queue Reconstruction by Height
Trapping Rain Water
The Skyline Problem
Largest Rectangle in Histogram