LeetCode is an online platform that provides a collection of coding challenges to help programmers and software engineers improve their coding skills and prepare for technical interviews. It covers a wide range of topics in computer science, including data structures, algorithms, databases, shell scripting, and more.
EASY
- Two Sum
- Palindrome Number
- Roman to Integer
- Longest Common Prefix
- Valid Parentheses
- Merge Two Sorted Lists
- Remove Duplicates from Sorted Array
- Remove Element
- Search Insert Position
- Length of Last Word
- Add Binary
- Sqrt(x)
- Climbing Stairs
- Remove Duplicates from Sorted List
- Merge Sorted Array
- Binary Tree Inorder Traversal
- Same Tree
- Symmetric Tree
- Maximum Depth of Binary Tree
- Convert Sorted Array to Binary Search Tree
- Plus One
- Balanced Binary Tree
- Minimum Depth of Binary Tree
- Path Sum
- Pascal’s Triangle
- Pascal’s Triangle II
- Best Time to Buy and Sell Stock
- Valid Palindrome
- Single Number
- Linked List Cycle
- Binary Tree Preorder Traversal
- Binary Tree Postorder Traversal
- Intersection of Two Linked Lists
- Excel Sheet Column Title
- Majority Element
- Excel Sheet Column Number
- Reverse Bits
- Number of 1 Bits
- Happy Number
- Remove Linked List Elements
- Isomorphic Strings
- Reverse Linked List
- Contains Duplicate
- Contains Duplicate II
- Implement Stack using Queues
- Invert Binary Tree
- Summary Ranges
- Power of Two
- Implement Queue using Stacks
- Palindrome Linked List
- Valid Anagram
- Binary Tree Paths
- Add Digits
- Ugly Number
- Missing Number
- First Bad Version
- Move Zeroes
- Word Pattern
- Nim Game
- Range Sum Query – Immutable
- Power of Three
- Counting Bits
- Power of Four
- Reverse String
- Reverse Vowels of a String
- Intersection of Two Arrays
- Intersection of Two Arrays II
- Valid Perfect Square
- Guess Number Higher or Lower
- Ransom Note
- First Unique Character in a String
- Find the Difference
- Is Subsequence
- Binary Watch
- Sum of Left Leaves
- Convert a Number to Hexadecimal
- Longest Palindrome
- Fizz Buzz
- Third Maximum Number
- Add Strings
- Number of Segments in a String
- Arranging Coins
- Find All Numbers Disappeared in an Array
- Assign Cookies
- Repeated Substring Pattern
- Hamming Distance
- Island Perimeter
- Number Complement
- License Key Formatting
- Max Consecutive Ones
- Construct the Rectangle
- Teemo Attacking
- Next Greater Element I
- Keyboard Row
- Find Mode in Binary Search Tree
- Base 7
- Relative Ranks
- Perfect Number
- Fibonacci Number
- Detect Capital
- Longest Uncommon Subsequence I
- Minimum Absolute Difference in BST
- Reverse String II
- Diameter of Binary Tree
- Student Attendance Record I
- Reverse Words in a String III
- Maximum Depth of N-ary Tree
- Array Partition
- Binary Tree Tilt
- Reshape the Matrix
- Subtree of Another Tree
- Distribute Candies
- N-ary Tree Preorder Traversal
- N-ary Tree Postorder Traversal
- Longest Harmonious Subsequence
- Range Addition II
- Minimum Index Sum of Two Lists
- Can Place Flowers
- Merge Two Binary Trees
- Maximum Product of Three Numbers
- Average of Levels in Binary Tree
- Maximum Average Subarray I
- Set Mismatch
- Two Sum IV – Input is a BST
- Robot Return to Origin
- Image Smoother
- Second Minimum Node In a Binary Tree
- Longest Continuous Increasing Subsequence
- Valid Palindrome II
- Baseball Game
- Binary Number with Alternating Bits
- Count Binary Substrings
- Degree of an Array
- Search in a Binary Search Tree
- Kth Largest Element in a Stream
- Design HashSet
- Design HashMap
- To Lower Case
- 1-bit and 2-bit Characters
- Find Pivot Index
- Self Dividing Numbers
- Flood Fill
- Find Smallest Letter Greater Than Target
- Min Cost Climbing Stairs
- Largest Number At Least Twice of Others
- Shortest Completing Word
- Prime Number of Set Bits in Binary Representation
- Toeplitz Matrix
- Jewels and Stones
- Minimum Distance Between BST Nodes
- Rotate String
- Unique Morse Code Words
- Number of Lines To Write String
- Largest Triangle Area
- Most Common Word
- Shortest Distance to a Character
- Goat Latin
- Positions of Large Groups
- Flipping an Image
- Rectangle Overlap
- Backspace String Compare
- Buddy Strings
- Lemonade Change
- Transpose Matrix
- Binary Gap
- Leaf-Similar Trees
- Middle of the Linked List
- Projection Area of 3D Shapes
- Uncommon Words from Two Sentences
- Fair Candy Swap
- Surface Area of 3D Shapes
- Monotonic Array
- Increasing Order Search Tree
- Sort Array By Parity
- Smallest Range I
- Reverse Only Letters
- Sort Array By Parity II
- Long Pressed Name
- Unique Email Addresses
- Number of Recent Calls
- Range Sum of BST
- Valid Mountain Array
- DI String Match
- Delete Columns to Make Sorted
- Verifying an Alien Dictionary
- N-Repeated Element in Size 2N Array
- Univalued Binary Tree
- Largest Perimeter Triangle
- Squares of a Sorted Array
- Add to Array-Form of Integer
- Cousins in Binary Tree
- Find the Town Judge
- Available Captures for Rook
- Find Common Characters
- Maximize Sum Of Array After K Negations
- Complement of Base 10 Integer
- Partition Array Into Three Parts With Equal Sum
- Binary Prefix Divisible By 5
- Remove Outermost Parentheses
- Sum of Root To Leaf Binary Numbers
- Divisor Game
- Matrix Cells in Distance Order
- Valid Boomerang
- Last Stone Weight
- Remove All Adjacent Duplicates In String
- Height Checker
- Greatest Common Divisor of Strings
- Occurrences After Bigram
- Duplicate Zeros
- Distribute Candies to People
- Defanging an IP Address
- Relative Sort Array
- Number of Equivalent Domino Pairs
- N-th Tribonacci Number
- Find Words That Can Be Formed by Characters
- Distance Between Bus Stops
- Day of the Week
- Maximum Number of Balloons
- Unique Number of Occurrences
- Minimum Cost to Move Chips to The Same Position
- Split a String in Balanced Strings
- Check If It Is a Straight Line
- Cells with Odd Values in a Matrix
- Minimum Time Visiting All Points
- Find Winner on a Tic Tac Toe Game
- Subtract the Product and Sum of Digits of an Integer
- Element Appearing More Than 25% In Sorted Array
- Convert Binary Number in a Linked List to Integer
- Find Numbers with Even Number of Digits
- Replace Elements with Greatest Element on Right Side
- Find N Unique Integers Sum up to Zero
- Decrypt String from Alphabet to Integer Mapping
- Decompress Run-Length Encoded List
- Convert Integer to the Sum of Two No-Zero Integers
- Maximum 69 Number
- Rank Transform of an Array
- Remove Palindromic Subsequences
- The K Weakest Rows in a Matrix
- Number of Steps to Reduce a Number to Zero
- Check If N and Its Double Exist
- Count Negative Numbers in a Sorted Matrix
- Sort Integers by The Number of 1 Bits
- How Many Numbers Are Smaller Than the Current Number
- Increasing Decreasing String
- Find a Corresponding Node of a Binary Tree in a Clone of That Tree
- Lucky Numbers in a Matrix
- Find the Distance Value Between Two Arrays
- Create Target Array in the Given Order
- Find Lucky Integer in an Array
- Count Largest Group
- Minimum Subsequence in Non-Increasing Order
- String Matching in an Array
- Minimum Value to Get Positive Step by Step Sum
- Reformat The String
- Maximum Score After Splitting a String
- Kids With the Greatest Number of Candies
- Destination City
- Check If All 1’s Are at Least Length K Places Away
- Consecutive Characters
- Number of Students Doing Homework at a Given Time
- Check If a Word Occurs As a Prefix of Any Word in a Sentence
- Make Two Arrays Equal by Reversing Subarrays
- Maximum Product of Two Elements in an Array
- Shuffle the Array
- Final Prices With a Special Discount in a Shop
- Running Sum of 1d Array
- XOR Operation in an Array
- Average Salary Excluding the Minimum and Maximum Salary
- Path Crossing
- Can Make Arithmetic Progression From Sequence
- Number of Good Pairs
- Water Bottles
- Count Odd Numbers in an Interval Range
- Count Good Triplets
- Kth Missing Positive Number
- Make The String Great
- Three Consecutive Odds
- Thousand Separator
- Most Visited Sector in a Circular Track
- Detect Pattern of Length M Repeated K or More Times
- Matrix Diagonal Sum
- Replace All ?’s to Avoid Consecutive Repeating Characters
- Special Positions in a Binary Matrix
- Sum of All Odd Length Subarrays
- Rearrange Spaces Between Words
- Crawler Log Folder
- Design Parking System
- Special Array With X Elements Greater Than or Equal X
- Maximum Nesting Depth of the Parentheses
- Mean of Array After Removing Some Elements
- Largest Substring Between Two Equal Characters
- Slowest Key
- Sort Array by Increasing Frequency
- Check Array Formation Through Concatenation
- Get Maximum in Generated Array
- Design an Ordered Stream
- Check If Two String Arrays are Equivalent
- Maximum Repeating Substring
- Richest Customer Wealth
- Goal Parser Interpretation
- Count the Number of Consistent Strings
- Count of Matches in Tournament
- Reformat Phone Number
- Number of Students Unable to Eat Lunch
- Determine if String Halves Are Alike
- Maximum Units on a Truck
- Decode XORed Array
- Number Of Rectangles That Can Form The Largest Square
- Find the Highest Altitude
- Latest Time by Replacing Hidden Digits
- Maximum Number of Balls in a Box
- Sum of Unique Elements
- Check if Array Is Sorted and Rotated
- Minimum Changes To Make Alternating Binary String
- Merge Strings Alternately
- Count Items Matching a Rule
- Find Nearest Point That Has the Same X or Y Coordinate
- Check if Binary String Has at Most One Segment of Ones
- Check if One String Swap Can Make Strings Equal
- Find Center of Star Graph
- Second Largest Digit in a String
- Maximum Ascending Subarray Sum
- Number of Different Integers in a String
- Truncate Sentence
- Sign of the Product of an Array
- Minimum Operations to Make the Array Increasing
- Check if the Sentence Is Pangram
- Sum of Digits in Base K
- Replace All Digits with Characters
- Minimum Distance to the Target Element
- Maximum Population Year
- Sorting the Sentence
- Sum of All Subset XOR Totals
- Longer Contiguous Segments of Ones than Zeros
- Check if Word Equals Summation of Two Words
- Check if All the Integers in a Range Are Covered
- Redistribute Characters to Make All Strings Equal
- Largest Odd Number in String
- Remove One Element to Make the Array Strictly Increasing