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Jul 17, 2026

LeetCode problem writeups — intuition, complexity, and solutions.

319 items under this folder.

Jul 17, 2026
Designing a Personal LeetCode Readiness Coach
Feb 28, 2026
Encode And Decode Tinyurl
- idea
Feb 23, 2026
Subtree Of Another Tree
- idea
Feb 22, 2026
Min Stack
- idea
Feb 21, 2026
Counting Bits
- idea
Feb 21, 2026
Reorder List
- idea
Feb 21, 2026
Valid Parenthesis String
- idea
Sep 22, 2025
Logger Rate Limiter
- idea
Sep 20, 2025
Remove Nodes From Linked List
- idea
Sep 19, 2025
Append Characters To String To Make Subsequence
- idea
Sep 19, 2025
Count Servers That Communicate
- idea
Mar 09, 2025
Number Of Islands
- idea
Mar 09, 2025
Partition To K Equal Sum Subsets
- idea
Mar 07, 2025
Minimum Recolors To Get K Consecutive Black Blocks
- idea
Mar 07, 2025
Sort Array By Parity
- idea
Mar 06, 2025
Simplify Path
- idea
Mar 03, 2025
Combinations
- idea
Mar 02, 2025
Trapping Rain Water
- idea
Feb 26, 2025
Maximum Absolute Sum Of Any Subarray
- idea
Feb 25, 2025
Number Of Sub Arrays With Odd Sum
- idea
Dec 15, 2024
Maximum Average Pass Ratio
- idea
Dec 14, 2024
Maximum Population Year
- idea
Dec 14, 2024
Points That Intersect With Cars
- idea
Dec 14, 2024
Ransom Note
- idea
Feb 28, 2024
Odd Even Linked List
- idea
Feb 25, 2024
Split Linked List In Parts
- idea
Feb 23, 2024
Best Time To Buy And Sell Stock II
- idea
Feb 20, 2024
Best Time To Buy And Sell Stock With Cooldown
- idea
Feb 20, 2024
Solving Questions With Brainpower
- idea
Feb 19, 2024
Best Team With No Conflicts
- idea
Feb 17, 2024
Count Odd Numbers In An Interval Range
- idea
Feb 16, 2024
Furthest Building You Can Reach
- idea
Feb 14, 2024
Design Browser History
- idea
Feb 14, 2024
Merge Triplets To Form Target Triplet
- idea
Feb 14, 2024
Minimum Cost For Tickets
- idea
Feb 13, 2024
Partition Labels
- idea
Feb 13, 2024
Rearrange Array Elements By Sign
- idea
Feb 13, 2024
Surrounded Regions
- idea
Feb 10, 2024
Task Scheduler II
- idea
Feb 10, 2024
Task Scheduler
- idea
Feb 07, 2024
Find The Kth Largest Integer In The Array
- idea
Feb 07, 2024
Kth Largest Element In An Array
- idea
Feb 06, 2024
Maximum Number Of Balloons
- idea
Feb 06, 2024
Range Sum Query Immutable
- idea
Jan 31, 2024
Monotonic Array
- idea
Jan 31, 2024
Next Greater Element I
- idea
Jan 24, 2024
Find Pivot Index
- idea
Jan 24, 2024
Pseudo Palindromic Paths In A Binary Tree
- idea
Jan 23, 2024
Binary Tree Paths
- idea
Jan 22, 2024
Promise Time Limit
- idea
Jan 20, 2024
Allow One Function Call
- idea
Jan 20, 2024
Function Composition
- idea
Jan 20, 2024
Sleep
- idea
Jan 14, 2024
Maximum Twin Sum Of A Linked List
- idea
Jan 14, 2024
Middle Of The Linked List
- idea
Jan 14, 2024
Reverse Linked List II
- idea
Jan 13, 2024
Design Hashset
- idea
Jan 13, 2024
Design Parking System
- idea
Jan 13, 2024
Determine If Two Strings Are Close
- idea
Jan 13, 2024
Minimum Number Of Steps To Make Two Strings Anagram
- idea
Jan 12, 2024
Determine If String Halves Are Alike
- idea
Jan 12, 2024
Fizz Buzz
- idea
Jan 12, 2024
Online Stock Span
- idea
Nov 25, 2023
Number Of Subsequences That Satisfy The Given Sum Condition
- idea
Nov 25, 2023
Sum Of Absolute Differences In A Sorted Array
- idea
Nov 24, 2023
Maximum Number Of Coins You Can Get
- idea
Nov 24, 2023
Redundant Connection
- idea
Nov 22, 2023
Extra Characters In A String
- idea
Nov 22, 2023
First Unique Character In A String
- idea
Nov 22, 2023
Longest Common Subsequence
- idea
Nov 22, 2023
Word Break
- idea
Nov 21, 2023
Fibonacci Number
- idea
Nov 21, 2023
Minimum Falling Path Sum
- idea
Nov 21, 2023
Paint House
- idea
Nov 21, 2023
Triangle
- idea
Nov 20, 2023
Baseball Game
- idea
Nov 20, 2023
Graph Valid Tree
- idea
Nov 20, 2023
Minimum Number Of Flips To Make The Binary String Alternating
- idea
Nov 18, 2023
Can Place Flowers
- idea
Nov 18, 2023
Find All Numbers Disappeared In An Array
- idea
Nov 18, 2023
Minimum Operations To Reduce X To Zero
- idea
Nov 18, 2023
Non Decreasing Array
- idea
Nov 18, 2023
Number Of Pairs Of Interchangeable Rectangles
- idea
Nov 18, 2023
Rotate Array
- idea
Oct 28, 2023
Count Vowels Permutation
- idea
Oct 28, 2023
Number Of Ways To Reach A Position After Exactly K Steps
- idea
Oct 28, 2023
Number Of Ways To Stay In The Same Place After Some Steps
- idea
Oct 23, 2023
Excel Sheet Column Number
- idea
Oct 23, 2023
Set Matrix Zeroes
- idea
Oct 23, 2023
Ugly Number
- idea
Oct 22, 2023
Happy Number
- idea
Oct 22, 2023
Plus One
- idea
Oct 20, 2023
Greatest Common Divisor Of Strings
- idea
Oct 15, 2023
Remove Duplicates From Sorted Array II
- idea
Oct 15, 2023
Remove Duplicates From Sorted Array
- idea
Oct 14, 2023
Binary Tree Zigzag Level Order Traversal
- idea
Oct 14, 2023
Find K Closest Elements
- idea
Oct 14, 2023
Symmetric Tree
- idea
Oct 13, 2023
The Maze II
- idea
Oct 13, 2023
The Maze
- idea
Oct 10, 2023
Longest Turbulent Subarray
- idea
Oct 07, 2023
Available Captures for Rook
- idea
Oct 07, 2023
Coin Change II
- idea
Oct 07, 2023
Coin Change
- idea
Oct 07, 2023
Maximum Depth of Binary Tree
- idea
Oct 07, 2023
N Queens
- idea
Oct 06, 2023
Array With Elements Not Equal to Average of Neighbors
- idea
Oct 06, 2023
Reverse Linked List
- idea
Oct 06, 2023
Swapping Nodes in a Linked List
- idea
Oct 06, 2023
Wiggle Sort
- idea
Oct 05, 2023
Majority Element II
- idea
Oct 05, 2023
Rotting Oranges
- idea
Oct 04, 2023
Count Complete Subarrays in an Array
- idea
Oct 04, 2023
Design Hashmap
- idea
Oct 04, 2023
Minimum Number of Food Buckets to Feed the Hamsters
- idea
Oct 04, 2023
Sort Vowels in a String
- idea
Oct 03, 2023
Number of Good Pairs
- idea
Sep 30, 2023
Reverse Words in a String III
- idea
Sep 30, 2023
Time Based Key-Value Store
- idea
Sep 26, 2023
Isomorphic Strings
- idea
Sep 26, 2023
Subarray Sum Equals K
- idea
Sep 25, 2023
Maximum Subarray
- idea
Sep 25, 2023
Product of Array Except Self
- idea
Sep 24, 2023
Maximum Product Subarray
- idea
Sep 24, 2023
Minimum Size Subarray Sum
- idea
Sep 23, 2023
Find the Duplicate Number
- idea
Sep 22, 2023
Pacific Atlantic Water Flow
- idea
Sep 22, 2023
Remove Covered Intervals
- idea
Sep 22, 2023
Walls and Gates
- idea
Sep 21, 2023
Design File System
- idea
Sep 21, 2023
Maximum Profit in Job Scheduling
- idea
Sep 21, 2023
Meeting Rooms II
- idea
Sep 19, 2023
Partition Equal Subset Sum
- idea
Sep 09, 2023
Combination Sum 2
- idea
Sep 04, 2023
Longest Palindrome by Concatenating Two Letter Words
- idea
Sep 04, 2023
Longest Palindrome
- idea
Sep 03, 2023
Search a 2D Matrix
- idea
Sep 03, 2023
Unique Paths 2
- idea
Sep 03, 2023
Unique Paths
- idea
Sep 01, 2023
LRU Cache
- idea
Aug 30, 2023
Copy List with Random Pointer
- idea
Aug 29, 2023
Longest Harmonious Subsequence
- idea
Aug 28, 2023
Binary Tree Right Side View
- idea
Aug 28, 2023
Count Good Nodes in Binary Tree
- idea
Aug 25, 2023
Construct Binary Search Tree from Preorder Traversal
- idea
Aug 25, 2023
Convert Sorted Array to Binary Search Tree
- idea
Aug 24, 2023
Hand of Straights
- idea
Aug 23, 2023
Longest String Chain
- idea
Aug 23, 2023
Maximum Total Importance of Roads
- idea
Aug 23, 2023
Reorganize String
- idea
Aug 23, 2023
Sort the Jumbled Numbers
- idea
Aug 23, 2023
Ways to Split Array into Good Subarrays
- idea
Aug 22, 2023
Concatenation of Array
- idea
Aug 22, 2023
Excel Sheet Column Title
- idea
Aug 21, 2023
Find the Index of the First Occurrence in a String
- idea
Aug 21, 2023
Repeated Substring Pattern
- idea
Jul 27, 2023
Predict the Winner
- idea
Jul 23, 2023
Check if Matrix Is X-Matrix
- idea
Jul 23, 2023
Check if One String Swap Can Make Strings Equal
- idea
Jul 14, 2023
Push Dominoes
- idea
Jul 14, 2023
Reverse Vowels of a String
- idea
Jul 14, 2023
Reverse Words in a String
- idea
Jul 11, 2023
Car Fleet
- idea
Jul 11, 2023
Maximum Number of Vowels in a Substring of Given Length
- idea
Jul 09, 2023
Fruit Into Baskets
- idea
Jul 08, 2023
Count Vowel Substrings of a String
- idea
Jul 08, 2023
Find Smallest Common Element in All Rows
- idea
Jul 08, 2023
Range Sum of Sorted Subarray Sums
- idea
Jul 07, 2023
Number of Good Ways to Split a String
- idea
Jun 30, 2023
Partition Array into Disjoint Intervals
- idea
Jun 30, 2023
Successful Pairs of Spells and Potions
- idea
Jun 27, 2023
Daily Temperatures
- idea
Jun 27, 2023
Move Zeroes
- idea
Jun 27, 2023
Symetric Tree
- idea
Jun 25, 2023
Valid Sudoku
- idea
Jun 04, 2023
Number of Provinces
- idea
Jun 03, 2023
Time Needed to Inform All Employees
- idea
May 31, 2023
Design Underground System
- idea
Apr 24, 2023
Contiguous Array
- idea
Apr 19, 2023
Longest ZigZag Path in a Binary Tree
- idea
Apr 18, 2023
Merge Strings Alternately
- idea
Apr 17, 2023
Kids With the Greatest Number of Candies
- idea
Apr 17, 2023
Non Overlapping Intervals
- idea
Apr 16, 2023
Course Schedule
- idea
Apr 14, 2023
Longest Palindromic Subsequence
- idea
Apr 13, 2023
Asteroid Collision
- idea
Apr 13, 2023
Validate Stack Sequences
- idea
Apr 11, 2023
Removing Stars From a String
- idea
Apr 10, 2023
Two Sum Less Than K
- idea
Apr 08, 2023
Restore IP Addresses
- idea
Apr 08, 2023
Subarray Product Less Than K
- idea
Apr 07, 2023
Number of Enclaves
- idea
Apr 05, 2023
Optimal Partition of String
- idea
Apr 05, 2023
Sort Colors
- idea
Apr 04, 2023
Print Immutable Linked List in Reverse
- idea
Apr 04, 2023
Remove Element
- idea
Apr 03, 2023
Boats to Save People
- idea
Apr 03, 2023
Gas Station
- idea
Apr 01, 2023
Decode Ways
- idea
Apr 01, 2023
Longest Increasing Subsequence (Coding)
- idea
Mar 31, 2023
4 Keys Keyboard
- idea
Mar 31, 2023
Pascals Triangle II
- idea
Mar 31, 2023
Pascals Triangle
- idea
Mar 29, 2023
Merge Intervals
- idea
Mar 27, 2023
Minimum Path Sum
- idea
Mar 26, 2023
Frequency of the Most Frequent Element
- idea
Mar 26, 2023
Longest Cycle in a Graph
- idea
Mar 26, 2023
Minimum Operations to Make Array Equal
- idea
Mar 26, 2023
Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold
- idea
Mar 25, 2023
Count Unreachable Pairs of Nodes in an Undirected Graph
- idea
Mar 25, 2023
Largest Perimeter Triangle
- idea
Mar 25, 2023
Minimum Difference Between Highest and Lowest of K Scores
- idea
Mar 25, 2023
Valid Triangle Number
- idea
Mar 23, 2023
Add Two Numbers
- idea
Mar 23, 2023
Number of Operations to Make Network Connected
- idea
Mar 22, 2023
Find Center of Star Graph
- idea
Mar 22, 2023
Find if Path Exists in Graph
- idea
Mar 22, 2023
Minimum Score of a Path Between Two Cities
- idea
Mar 22, 2023
Number of Connected Components in an Undirected Graph
- idea
Mar 22, 2023
Web Crawler
- idea
Mar 21, 2023
Find First Palindromic String in the Array
- idea
Mar 21, 2023
Letter Combinations of a Phone Number
- idea
Mar 21, 2023
Palindrome Partitioning
- idea
Mar 21, 2023
Shuffle the Array
- idea
Mar 21, 2023
Smallest Even Multiple
- idea
Mar 18, 2023
Subsets II
- idea
Mar 17, 2023
Find First and Last Position of Element in Sorted Array
- idea
Mar 16, 2023
Max Consecutive Ones
- idea
Mar 16, 2023
Permutation in String
- idea
Mar 14, 2023
Sum Root to Leaf Numbers
- idea
Mar 13, 2023
Evaluate Reverse Polish Notation
- idea
Mar 08, 2023
Koko Eating Bananas
- idea
Mar 07, 2023
Buddy Strings
- idea
Mar 07, 2023
Construct Binary Tree from Preorder and Inorder Traversal
- idea
Mar 07, 2023
Longest Common Prefix
- idea
Mar 07, 2023
Majority Element
- idea
Mar 06, 2023
Valid Palindrome II
- idea
Mar 05, 2023
Length of Last Word
- idea
Mar 04, 2023
Find Median from Data Stream
- idea
Mar 04, 2023
Kth Largest Element in a Stream
- idea
Mar 02, 2023
Minimum Cost to Move Chips to the Same Position
- idea
Mar 02, 2023
Reverse String
- idea
Mar 01, 2023
Is Subsequence
- idea
Mar 01, 2023
Unique Email Addresses
- idea
Feb 28, 2023
Kth Smallest Element in a BST
- idea
Feb 27, 2023
Permutations
- idea
Feb 26, 2023
Arranging Coins
- idea
Feb 26, 2023
Guess Number Higher or Lower
- idea
Feb 26, 2023
Insert Interval
- idea
Feb 26, 2023
Replace Elements with Greatest Element on Right Side
- idea
Feb 26, 2023
Search Insert Position
- idea
Feb 26, 2023
Subsets
- idea
Feb 24, 2023
Island Perimeter
- idea
Feb 24, 2023
Palindromic Substrings
- idea
Feb 23, 2023
Intersection of Two Linked Lists
- idea
Feb 23, 2023
Remove Linked List Elements
- idea
Feb 22, 2023
Palindrome Number
- idea
Feb 22, 2023
Remove Duplicates from Sorted List
- idea
Feb 21, 2023
Construct String From Binary Tree
- idea
Feb 21, 2023
Merge Two Binary Trees
- idea
Feb 21, 2023
Palindrome Linked List
- idea
Feb 21, 2023
Path Sum
- idea
Feb 20, 2023
Balanced Binary Tree
- idea
Feb 19, 2023
Clone Graph
- idea
Feb 19, 2023
Diameter of a Binary Tree
- idea
Feb 19, 2023
Generate Parentheses
- idea
Feb 19, 2023
Lowest Common Ancestor of a Binary Search Tree
- idea
Feb 19, 2023
Search in Rotated Sorted Array
- idea
Feb 17, 2023
Binary Search Coded
- idea
Feb 17, 2023
Merge Sorted Array
- idea
Feb 17, 2023
Word Search
- idea
Feb 16, 2023
Minimum Distance Between BST Nodes
- idea
Feb 15, 2023
Combination Sum
- idea
Feb 12, 2023
Container With Most Water
- idea
Feb 12, 2023
House Robber II
- idea
Feb 12, 2023
Longest Repeating Character Placement
- idea
Feb 11, 2023
Min Cost Climbing Stairs
- idea
Feb 10, 2023
3Sum
- idea
Feb 10, 2023
Two Sum II- Input Array Is Sorted
- idea
Feb 08, 2023
House Robber
- idea
Feb 07, 2023
Spiral Matrix
- idea
Feb 06, 2023
Rotate Image
- idea
Feb 06, 2023
Validate Binary Search Tree
- idea
Feb 05, 2023
Binary Tree Inorder Traversal
- idea
Feb 05, 2023
Binary Tree Level Order Traversal
- idea
Feb 05, 2023
Binary Tree Postorder Traversal
- idea
Feb 05, 2023
Binary Tree Preorder Traversal
- idea
Feb 04, 2023
Big Countries
- idea
Feb 04, 2023
Rotating the Box
- idea
Feb 03, 2023
Design Add and Search Words Data Structure
- idea
Feb 03, 2023
Longest Consecutive Sequence
- idea
Feb 02, 2023
Encode and Decode Strings
- idea
Feb 02, 2023
Verifying An Alien Dictionary
- idea
Feb 01, 2023
Implement Trie Prefix Tree
- idea
Feb 01, 2023
Jump Game
- idea
Feb 01, 2023
Longest Substring Without Repeating Characters
- idea
Jan 31, 2023
Remove Nth Node From Linked List
- idea
Jan 25, 2023
Find Minimum in Rotated Sorted Array
- idea
Jan 23, 2023
Meeting Rooms
- idea
Jan 23, 2023
Number of 1 Bits
- idea
Jan 23, 2023
Reverse Bits
- idea
Jan 22, 2023
Climbing Stairs
- idea
Jan 22, 2023
Missing Number
- idea
Jan 21, 2023
Same Tree
- idea
Jan 20, 2023
Invert Binary Tree
- idea
Jan 20, 2023
Linked List Cycle
- idea
Jan 19, 2023
Merge Two Linked Lists
- idea
Jan 17, 2023
Valid Parantheses
- idea
Jan 16, 2023
Valid Palindrome
- idea
Jan 15, 2023
Group Anagrams
- idea
Jan 15, 2023
Top K Frequent Elements
- idea
Jan 14, 2023
Contains Duplicate II
- idea
Jan 14, 2023
Contains Duplicate
- idea
Jan 14, 2023
Longest Palindromic Substring
- idea
Jan 14, 2023
Regular Expression Matching
- idea
Jan 14, 2023
Two Sum
- idea
Jan 14, 2023
Valid Anagram
- idea
Jan 13, 2023
Best Time To Buy And Sell Stock
- idea
Sep 22, 2022
Max Area of Island
- idea

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