Check if a string is a Palindrome

Sum of Two Primes

Valid URL Checker

Maximum Subarray Length with Given Sum

Longest Substring Without Repeating Characters

Minimum Window Substring

Count Vowels and Consonants

Longest Increasing Subsequence

Solve Sudoku Board

Find First Repeated Character

String Compression

Calculate Greatest Common Divisor

Subarray Sum

Find the Missing Number

Rotate Matrix

Duplicate Characters

Maximum Product Subarray

Maximum Subarray Sum

Shortest Distance to a Character

Array Duplicate Elements

Longest Palindromic Substring

Maximum Sum of Non-adjacent Elements

Maximum Difference Between Two Elements in an Array

Longest Substring with At Least K Repeating Characters

Reverse Words in a String

Shortest Word Distance

Matrix Cells in Distance Order

Count Primes in Range

Maximum Consecutive Ones

Find All Duplicates in an Array

Repeated String Match

Count of Smaller Numbers After Self

Task Scheduler - Least Intervals

Island Perimeter

Reverse Vowels of a String

Decode String

Valid Parentheses

Repeated Substring Pattern

Longest Common Prefix

Maximum Occurring Characters in a String

Closest Palindromic Substring

Majority Element

Median of Two Sorted Arrays

Integer to Roman

Roman to Integer

Phone Number Validation

Maximum Water Capacity

Three Elements Sum

Four Elements Sum

Merge Two Sorted Lists

Remove Duplicates from Sorted Array

Next Permutation

Longest Valid Parentheses

Valid Sudoku Board

First Missing Positive

Collected Rain Water

Strings Multiplication

All Permutations of a String

K Permutations of an Array

Placing Queens on Chessboard

Spiral Matrix Elements

Merge Intervals

Length of Last Word

Kth Permutation Sequence

Valid Number

Binary Addition

Climbing Stairs

Simplify Path

Set Matrix Zeroes

Target Sum

Next Greater Element

 Diameter of Binary Tree

Palindrome Partitioning

 Container With Most Water

Find Missing Number in Array

Invert Binary Tree

Group Anagrams

Subarray Sum Equals K

 K Closest Points to Origin

Largest Rectangle in Histogram

Valid Anagram

Product of Array Except Self

Graph Valid Tree

Find Median in a Stream

Longest Repeating Character Replacement

Longest Increasing Path in a Matrix

Max Consecutive Ones

Find Minimum in Rotated Sorted Array

Intersection of Two Linked Lists

Symmetric Tree

Find Peak Element

First Bad Version

Swap Nodes in Pairs

Move Zeroes

Search a 2D Matrix

ZigZag Conversion

Binary Tree Level Order Traversal

Count the Triplets

N Meetings in One Room

Tower of Hanoi

Question
Flatten a Binary Tree
Remove K Digits
Maximum Sum Combinations
Check if Array is Sorted
Book Allocation Problem
Count Subsets with Sum K
Optimal Binary Search Tree
Next Smaller Element
M Coloring Problem
Sort a Stack
Bottom View of Binary Tree
Delete Middle Element of a Stack
Shortest Path in Directed Acyclic Graph
Path Sum
Balanced Binary Tree
Distinct Subsequences
Pascal's Triangle
Convert Sorted Array to Binary Search Tree
Best Time to Buy and Sell Stock
Factorial Trailing Zeroes
Repeated DNA Sequences
Compare Version Numbers
Binary Tree Preorder Traversal
Reorder List
Largest Number
Reverse Linked List
Isomorphic Strings
Bitwise AND of Numbers Range
Happy Number
Kth Largest Element in an Array

Problems library (weekly updates)