Patterns Index

Browse all solutions. Use the dropdowns to filter by difficulty or pattern.

Solution	Difficulty	Pattern
Add Binary	🟢 Easy	Math, String, Bit Manipulation, Simulation
Add Two Numbers	🟡 Medium	Linked List, Math, Recursion
Best Time To Buy And Sell Stock	🟢 Easy	Array, Dynamic Programming
Binary Tree Inorder Traversal	🟢 Easy	Stack, Tree, Depth-First Search, Binary Tree
Binary Tree Level Order Traversal	🟡 Medium	Tree, Breadth-First Search, Binary Tree
Binary Tree Zigzag Level Order Traversal	🟡 Medium	Tree, Breadth-First Search, Binary Tree
Bitwise AND Of Numbers Range	🟡 Medium	Bit Manipulation
Climbing Stairs	🟢 Easy	Math, Dynamic Programming, Memoization
Construct Binary Tree From Preorder And Inorder Traversal	🟡 Medium	Array, Hash Table, Divide and Conquer, Tree, Binary Tree
Container With Most Water	🟡 Medium	Array, Two Pointers, Greedy
Contains Duplicate II	🟢 Easy	Array, Hash Table, Sliding Window
Convert Sorted Array To BST	🟢 Easy	Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree
Count And Say	🟡 Medium	String
Count Primes	🟡 Medium	Array, Math, Enumeration, Number Theory
Delete Node In A Linked List	🟡 Medium	Linked List
Divide Two Integers	🟡 Medium	Math, Bit Manipulation
Find First And Last Position Of Element In Sorted Array	🟡 Medium	Array, Binary Search
Find The Index Of The First Occurrence In A String	🟢 Easy	Two Pointers, String, String Matching
First Unique Character In A String	🟢 Easy	Hash Table, String, Queue, Counting
Fizz Buzz	🟢 Easy	Math, String, Simulation
Game Of Life	🟡 Medium	Array, Matrix, Simulation
Gas Station	🟡 Medium	Array, Greedy
Generate Parentheses	🟡 Medium	String, Dynamic Programming, Backtracking
Group Anagrams	🟡 Medium	Array, Hash Table, String, Sorting
H Index	🟡 Medium	Array, Sorting, Counting Sort
Happy Number	🟢 Easy	Hash Table, Math, Two Pointers
Insert Delete Get Random O1	🟡 Medium	Array, Hash Table, Math, Design, Randomized
Integer To Roman	🟡 Medium	Hash Table, Math, String
Intersection Of Two Arrays II	🟢 Easy	Array, Hash Table, Two Pointers, Binary Search, Sorting
Intersection Of Two Linked Lists	🟢 Easy	Hash Table, Linked List, Two Pointers
Invert Binary Tree	🟢 Easy	Tree, Depth-First Search, Breadth-First Search, Binary Tree
Is Subsequence	🟢 Easy	Two Pointers, String, Dynamic Programming
Isomorphic Strings	🟢 Easy	Hash Table, String
Jump Game	🟡 Medium	Array, Dynamic Programming, Greedy
LRU Cache	🟡 Medium	Hash Table, Linked List, Design, Doubly-Linked List
Length Of Last Word	🟢 Easy	String
Length Of Longest Substring	🟡 Medium	Hash Table, String, Sliding Window
Letter Combinations Of A Phone Number	🟡 Medium	Hash Table, String, Backtracking
Linked List Cycle	🟢 Easy	Hash Table, Linked List, Two Pointers
Longest Common Prefix	🟢 Easy	Array, String, Trie
Longest Palindromic Substring	🟡 Medium	Two Pointers, String, Dynamic Programming
Majority Element	🟢 Easy	Array, Hash Table, Divide and Conquer, Sorting, Counting
Maximum Depth Of Binary Tree	🟢 Easy	Tree, Depth-First Search, Breadth-First Search, Binary Tree
Maximum Subarray	🟡 Medium	Array, Divide and Conquer, Dynamic Programming
Merge Intervals	🟡 Medium	Array, Sorting
Merge K Sorted Lists	🔴 Hard	Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort
Merge Sorted Array	🟢 Easy	Array, Two Pointers, Sorting
Merge Two Sorted Lists	🟢 Easy	Linked List, Recursion
Missing Number	🟢 Easy	Array, Hash Table, Math, Binary Search, Bit Manipulation, Sorting
Palindrome Linked List	🟢 Easy	Linked List, Two Pointers, Stack, Recursion
Palindrome Number	🟢 Easy	Math
Pascals Triangle	🟢 Easy	Array, Dynamic Programming
Permutations	🟡 Medium	Array, Backtracking
Plus One	🟢 Easy	Array, Math
Pow	🟡 Medium	Math, Recursion
Power Of Three	🟢 Easy	Math, Recursion
Product Of Array Except Self	🟡 Medium	Array, Prefix Sum
Ransom Note	🟢 Easy	Hash Table, String, Counting
Remove Duplicates From Sorted Array II	🟡 Medium	Array, Two Pointers
Remove Element	🟢 Easy	Array, Two Pointers
Remove Nth Node From End Of List	🟡 Medium	Linked List, Two Pointers
Reverse Integer	🟡 Medium	Math
Reverse Linked List	🟢 Easy	Linked List, Recursion
Reverse String	🟢 Easy	Two Pointers, String
Reverse Words In A String	🟡 Medium	Two Pointers, String
Roman To Integer	🟢 Easy	Hash Table, Math, String
Rotate Image	🟡 Medium	Array, Math, Matrix
Same Tree	🟢 Easy	Tree, Depth-First Search, Breadth-First Search, Binary Tree
Search In Rotated Array	🟡 Medium	Array, Binary Search
Set Matrix Zeroes	🟡 Medium	Array, Hash Table, Matrix
Single Number II	🟡 Medium	Array, Bit Manipulation
Sort List	🟡 Medium	Linked List, Two Pointers, Divide and Conquer, Sorting, Merge Sort
Sqrtx	🟢 Easy	Math, Binary Search
String To Integer	🟡 Medium	String
Subsets	🟡 Medium	Array, Backtracking, Bit Manipulation
Summary Ranges	🟢 Easy	Array
Symmetric Tree	🟢 Easy	Tree, Depth-First Search, Breadth-First Search, Binary Tree
Three Sum	🟡 Medium	Array, Two Pointers, Sorting
Tries	🟡 Medium	Trie
Two Sum	🟢 Easy	Array, Hash Table
Two Sum II	🟡 Medium	Array, Two Pointers, Binary Search
Valid Anagram	🟢 Easy	Hash Table, String, Sorting
Valid Palindrome	🟢 Easy	Two Pointers, String
Valid Parentheses	🟢 Easy	String, Stack
Valid Sudoku	🟡 Medium	Array, Hash Table, Matrix
Word Pattern	🟢 Easy	Hash Table, String
Zig Zag Conversion	🟡 Medium	String