Easy (31/31)	Medium (73/73)	Hard (45/58)	Very Hard (1/38)
Binary Search	Array Of Products	Ambiguous Measurements	A* Algorithm
Branch Sums	BST Construction	Boggle Board	Airport Connections
Bubble Sort	BST Traversal	Continuous Median	All Kinds Of Node Depths
Caesar Cipher Encryptor	Balanced Brackets	Count Squares	Apartment Hunting
Class Photos	Best Digits	Dice Throws	Calendar Matching
Common Characters	Best Seat	Dijkstra's Algorithm	Compare Leaf Traversal
Depth-first Search	Binary Tree Diameter	Disk Stacking	Count Inversions
Evaluate Expression Tree	Blackjack Probability	Find Loop	Detect Arbitrage
Find Closest Value In BST	Breadth-first Search	Find Nodes Distance K	Flatten Binary Tree
Find Three Largest Numbers	Colliding Asteroids	Four Number Sum	Iterative In-order Traversal
First Non-Repeating Character	Cycle In Graph	Generate Div Tags	Knuth—Morris—Pratt Algorithm
Generate Document	Find Kth Largest Value In BST	Heap Sort	LRU Cache
Insertion Sort	Find Successor	Index Equals Value	Largest Park
Middle Node	First Duplicate Value	Interweaving Strings	Line Through Points
Minimum Waiting Time	Group Anagrams	Juice Bottling	Linked List Palindrome
Node Depths	Height Balanced Binary Tree	Knapsack Problem	Longest Balanced Substring
Non-Constructible Change	Invert Binary Tree	Knight Connection	Longest Increasing Subsequence
Nth Fibonacci	Kadane's Algorithm	Kruskal's Algorithm	Longest String Chain
Optimal Freelancing	Levenshtein Distance	Laptop Rentals	Max Profit With K Transactions
Palindrome Check	Linked List Construction	Largest Island	Median Of Two Sorted Arrays
Product Sum	Longest Palindromic Substring	Largest Range	Merge Sort
Remove Duplicates From Linked List	Longest Peak	Largest Rectangle Under Skyline	Merge Sorted Arrays
Run-Length Encoding	Majority Element	Longest Common Subsequence	Minimum Area Rectangle
Selection Sort	Max Subset Sum No Adjacent	Longest Most Frequent Prefix	Node Swap
Semordnilap	Merge Binary Trees	Longest Subarray With Sum	Non-Attacking Queens
Sorted Squared Array	Merge Overlapping Intervals	Longest Substring Without Duplication	Number Of Binary Tree Topologies
Tandem Bicycle	Merging Linked Lists	Lowest Common Manager	Optimal Assembly Line
Tournament Winner	Min Heap Construction	Max Path Sum In Binary Tree	Palindrome Partitioning Min Cuts
Transpose Matrix	Min Height BST	Max Sum Increasing Subsequence	Rearrange Linked List
Two Number Sum	Min Max Stack Construction	Maximize Expression	Rectangle Mania
Validate Subsequence	Min Number Of Coins For Change	Maximum Sum Submatrix	Right Sibling Tree
	Minimum Characters For Words	Merge Linked Lists	Right Smaller Than
	Minimum Passes Of Matrix	Min Number Of Jumps	Smallest Substring Containing
	Missing Numbers	Min Rewards	Square of Zeroes
	Monotonic Array	Multi String Search	Strings Made Up Of Strings
	Move Element To End	Numbers In Pi	Two-Edge-Connected Graph
	Next Greater Element	Pattern Matcher	Waterfall Streams
	Number Of Ways To Make Change	Prim's Algorithm	Zip Linked List
	Number Of Ways To Traverse Graph	Quick Sort
	One Edit	Quickselect
	Permutations	Radix Sort
	Phone Number Mnemonics	Repair BST
	Powerset	Reverse Linked List
	Reconstruct BST	Same BSTs
	Remove Islands	Search For Range
	Remove Kth Node From End	Shift Linked List
	Reveal Minesweeper	Shifted Binary Search
	Reverse Polish Notation	Shorten Path
	Reverse Words In String	Shortest Unique Prefixes
	River Sizes	Solve Sudoku
	Search In Sorted Matrix	Sort K-Sorted Array
	Single Cycle Check	Subarray Sort
	Smallest Difference	Sum BSTs
	Sort Stack	Topological Sort
	Spiral Traverse	Underscorify Substring
	Split Binary Tree	Validate Three Nodes
	Stable internships	Water Area
	Staircase Traversal	Zigzag Traverse
	Suffix Trie Construction
	Sum of Linked Lists
	Sunset Views
	Sweet And Savory
	Symmetrical Tree
	Task Assignment
	Three Number Sort
	Three Number Sum
	Two-Colorable
	Union Find
	Valid IP Addresses
	Valid Starting City
	Validate BST
	Youngest Common Ancestor
	Zero Sum Subarray

Group by category

Arrays (28/33)

Name	Difficulty
Tournament Winner	Easy
Two Number Sum	Easy
Non-Constructible Change	Easy
Validate Subsequence	Easy
Transpose Matrix	Easy
Sorted Squared Array	Easy
Majority Element	Medium
Missing Numbers	Medium
Spiral Traverse	Medium
Sweet And Savory	Medium
Move Element To End	Medium
Monotonic Array	Medium
Zero Sum Subarray	Medium
Merge Overlapping Intervals	Medium
Longest Peak	Medium
Array Of Products	Medium
Best Seat	Medium
First Duplicate Value	Medium
Smallest Difference	Medium
Three Number Sum	Medium
Knight Connection	Hard
Count Squares	Hard
Four Number Sum	Hard
Subarray Sort	Hard
Longest Subarray With Sum	Hard
Largest Range	Hard
Zigzag Traverse	Hard
Min Rewards	Hard
Apartment Hunting	Very Hard
Line Through Points	Very Hard
Minimum Area Rectangle	Very Hard
Waterfall Streams	Very Hard
Calendar Matching	Very Hard

Binary Search Trees (11/12)

Name	Difficulty
Find Closest Value In BST	Easy
BST Construction	Medium
Validate BST	Medium
BST Traversal	Medium
Min Height BST	Medium
Find Kth Largest Value In BST	Medium
Reconstruct BST	Medium
Same BSTs	Hard
Validate Three Nodes	Hard
Repair BST	Hard
Sum BSTs	Hard
Right Smaller Than	Very Hard

Binary Trees (12/17)

Name	Difficulty
Node Depths	Easy
Evaluate Expression Tree	Easy
Branch Sums	Easy
Merge Binary Trees	Medium
Invert Binary Tree	Medium
Binary Tree Diameter	Medium
Split Binary Tree	Medium
Symmetrical Tree	Medium
Find Successor	Medium
Height Balanced Binary Tree	Medium
Max Path Sum In Binary Tree	Hard
Find Nodes Distance K	Hard
All Kinds Of Node Depths	Very Hard
Compare Leaf Traversal	Very Hard
Right Sibling Tree	Very Hard
Flatten Binary Tree	Very Hard
Iterative In-order Traversal	Very Hard

Dynamic Programming (17/21)

Name	Difficulty
Number Of Ways To Traverse Graph	Medium
Number Of Ways To Make Change	Medium
Min Number Of Coins For Change	Medium
Max Subset Sum No Adjacent	Medium
Levenshtein Distance	Medium
Knapsack Problem	Hard
Min Number Of Jumps	Hard
Water Area	Hard
Longest Common Subsequence	Hard
Disk Stacking	Hard
Max Sum Increasing Subsequence	Hard
Juice Bottling	Hard
Dice Throws	Hard
Numbers In Pi	Hard
Maximize Expression	Hard
Maximum Sum Submatrix	Hard
Max Profit With K Transactions	Very Hard
Square of Zeroes	Very Hard
Longest String Chain	Very Hard
Longest Increasing Subsequence	Very Hard
Palindrome Partitioning Min Cuts	Very Hard

Famous Algorithms (6/9)

Name	Difficulty
Kadane's Algorithm	Medium
Stable internships	Medium
Union Find	Medium
Dijkstra's Algorithm	Hard
Topological Sort	Hard
Kruskal's Algorithm	Hard
Prim's Algorithm	Hard
Knuth—Morris—Pratt Algorithm	Very Hard
A* Algorithm	Very Hard

Graphs (9/15)

Name	Difficulty
Depth-first Search	Easy
Minimum Passes Of Matrix	Medium
Single Cycle Check	Medium
Breadth-first Search	Medium
River Sizes	Medium
Youngest Common Ancestor	Medium
Remove Islands	Medium
Cycle In Graph	Medium
Two-Colorable	Medium
Boggle Board	Hard
Largest Island	Hard
Rectangle Mania	Very Hard
Airport Connections	Very Hard
Two-Edge-Connected Graph	Very Hard
Detect Arbitrage	Very Hard

Greedy Algorithms (6/6)

Name	Difficulty
Minimum Waiting Time	Easy
Class Photos	Easy
Tandem Bicycle	Easy
Optimal Freelancing	Easy
Task Assignment	Medium
Valid Starting City	Medium

Heaps (1/5)

Name	Difficulty
Min Heap Construction	Medium
Continuous Median	Hard
Sort K-Sorted Array	Hard
Laptop Rentals	Hard
Merge Sorted Arrays	Very Hard

Linked Lists (10/15)

Name	Difficulty
Middle Node	Easy
Remove Duplicates From Linked List	Easy
Linked List Construction	Medium
Remove Kth Node From End	Medium
Merging Linked Lists	Medium
Sum of Linked Lists	Medium
Shift Linked List	Hard
Merge Linked Lists	Hard
Reverse Linked List	Hard
Find Loop	Hard
Rearrange Linked List	Very Hard
Linked List Palindrome	Very Hard
Zip Linked List	Very Hard
Node Swap	Very Hard
LRU Cache	Very Hard

Recursion (9/15)

Name	Difficulty
Product Sum	Easy
Nth Fibonacci	Easy
Staircase Traversal	Medium
Permutations	Medium
Powerset	Medium
Reveal Minesweeper	Medium
Blackjack Probability	Medium
Phone Number Mnemonics	Medium
Solve Sudoku	Hard
Interweaving Strings	Hard
Generate Div Tags	Hard
Ambiguous Measurements	Hard
Lowest Common Manager	Hard
Non-Attacking Queens	Very Hard
Number Of Binary Tree Topologies	Very Hard

Searching (7/9)

Name	Difficulty
Binary Search	Easy
Find Three Largest Numbers	Easy
Search In Sorted Matrix	Medium
Shifted Binary Search	Hard
Search For Range	Hard
Quickselect	Hard
Index Equals Value	Hard
Median Of Two Sorted Arrays	Very Hard
Optimal Assembly Line	Very Hard

Sorting (6/9)

Name	Difficulty
Bubble Sort	Easy
Insertion Sort	Easy
Selection Sort	Easy
Three Number Sort	Medium
Quick Sort	Hard
Heap Sort	Hard
Radix Sort	Hard
Merge Sort	Very Hard
Count Inversions	Very Hard

Stacks (10/11)

Name	Difficulty
Min Max Stack Construction	Medium
Balanced Brackets	Medium
Sunset Views	Medium
Best Digits	Medium
Sort Stack	Medium
Next Greater Element	Medium
Reverse Polish Notation	Medium
Colliding Asteroids	Medium
Shorten Path	Hard
Largest Rectangle Under Skyline	Hard
Largest Park	Very Hard

Strings (15/18)

Name	Difficulty
Common Characters	Easy
Caesar Cipher Encryptor	Easy
Run-Length Encoding	Easy
Semordnilap	Easy
First Non-Repeating Character	Easy
Generate Document	Easy
Palindrome Check	Easy
Longest Palindromic Substring	Medium
One Edit	Medium
Reverse Words In String	Medium
Group Anagrams	Medium
Minimum Characters For Words	Medium
Valid IP Addresses	Medium
Longest Substring Without Duplication	Hard
Pattern Matcher	Hard
Underscorify Substring	Hard
Smallest Substring Containing	Very Hard
Longest Balanced Substring	Very Hard

Tries (3/5)

Name	Difficulty
Suffix Trie Construction	Medium
Multi String Search	Hard
Longest Most Frequent Prefix	Hard
Shortest Unique Prefixes	Hard
Strings Made Up Of Strings	Very Hard