📘 Collection of 225 leetcode problems. Includes solutions and quizzes/questions/tests in flashcards format (Anki) to learn patterns/techniques.
- 🚀 NeetCode
🅱️ Blind- 🥇 LeetCode
- 🧩 Sean Prashad
- 🏫 Tech interview handbook
- 🧑💻 Hackernoon
Disclaimer: Some of the questions are taken from neetcode.io/practice, only the questions that correspond to the "free" category were used, the content belongs to neetcode and is only being used for educational purposes.
The questions in this section are designed to help you remember the patterns or techniques used throughout the problems. The problems are in a Q&A format, this is to facilitate the creation of a deck of Anki cards.
The order is based on the roadmap created by neetcode
| Symbol | Meaning |
|---|---|
| ✅ | Transcribed/created questions (may need revision) |
| 📘 | Questions that may need to be transcribed |
| Questions that do not appear on neetcode.io or are behind a paywall and need to be created | |
| [Blind] | Question part of Blind 75 original post |
| [Ex] | Extra question that is not in that category in neetcode.io/roadmap |
| [ComEx] | Extra question considered within blind by the community |
◽ - Dynamic Arrays - Data Structures & Algorithms for Beginners
◽ - Hash Usage - Data Structures & Algorithms for Beginners
◽ - Hash Implementation - Data Structures & Algorithms for Beginners
◽ - Prefix Sums - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0217 | Contains Duplicate - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0242 | Valid Anagram - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0001 | Two Sum - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0049 | Group Anagrams - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅ |
| 0347 | Top K Frequent Elements - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0271 | Encode and Decode Strings - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0238 | Product of Array Except Self - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0036 | Valid Sudoku | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0128 | Longest Consecutive Sequence - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
◽ - Two Pointers - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0125 | Valid Palindrome - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0167 | Two Sum II Input Array Is Sorted | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0015 | 3Sum - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0011 | Container With Most Water - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0042 | Trapping Rain Water | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Stacks - Data Structures & Algorithms for Beginners
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0020 | Valid Parentheses - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0155 | Min Stack | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0150 | Evaluate Reverse Polish Notation | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0022 | Generate Parentheses | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0739 | Daily Temperatures | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0853 | Car Fleet | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0084 | Largest Rectangle In Histogram | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Search Array - Data Structures & Algorithms for Beginners
◽ - Search Range - Data Structures & Algorithms for Beginners
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0704 | Binary Search | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0074 | Search a 2D Matrix | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0875 | Koko Eating Bananas | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0153 | Find Minimum In Rotated Sorted Array - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0033 | Search In Rotated Sorted Array - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0981 | Time Based Key Value Store | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0004 | Median of Two Sorted Arrays | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Sliding Window Fixed Size - Advanced Algorithms
◽ - Sliding Window Variable Size - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0121 | Best Time to Buy And Sell Stock - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0003 | Longest Substring Without Repeating Characters - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0424 | Longest Repeating Character Replacement - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0567 | Permutation In String | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0076 | Minimum Window Substring - [Blind] | Link | Hard | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0239 | Sliding Window Maximum | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Singly Linked Lists - Data Structures & Algorithms for Beginners
◽ - Doubly Linked Lists - Data Structures & Algorithms for Beginners
◽ - Fast and Slow Pointers - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0206 | Reverse Linked List - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0021 | Merge Two Sorted Lists - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0143 | Reorder List - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0019 | Remove Nth Node From End of List - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | ✅📘 |
| 0138 | Copy List With Random Pointer | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0002 | Add Two Numbers | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0141 | Linked List Cycle - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0287 | Find The Duplicate Number | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0146 | LRU Cache | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0023 | Merge K Sorted Lists - [Blind] | Link | Hard | YouTube | Typescript | N/A | N/A | |
| 0025 | Reverse Nodes In K Group | Link | Hard | YouTube | Typescript | N/A | N/A | ✅📘 |
◽ - BST Insert and Remove - Data Structures & Algorithms for Beginners
◽ - Depth-First Search - Data Structures & Algorithms for Beginners
◽ - Breadth-First Search - Data Structures & Algorithms for Beginners
◽ - BST Sets and Maps - Data Structures & Algorithms for Beginners
◽ - Iterative DFS - Advanced Algorithms
◽ - Trie - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0208 | Implement Trie Prefix Tree - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0211 | Design Add And Search Words Data Structure - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0212 | Word Search II - [Blind] | Link | Hard | YouTube | N/A | N/A | N/A |
◽ - Tree Maze - Data Structures & Algorithms for Beginners
◽ - Subsets - Advanced Algorithms
◽ - Combinations - Advanced Algorithms
◽ - Permutations - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0078 | Subsets | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0039 | Combination Sum - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0046 | Permutations | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0090 | Subsets II | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0040 | Combination Sum II | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0079 | Word Search - [Blind] | Link | Medium | YouTube | N/A | N/A | N/A | |
| 0131 | Palindrome Partitioning | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0017 | Letter Combinations of a Phone Number | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0051 | N Queens | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Heap Properties - Data Structures & Algorithms for Beginners
◽ - Push and Pop - Data Structures & Algorithms for Beginners
◽ - Heapify - Data Structures & Algorithms for Beginners
◽ - Two Heaps - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| N/A | Kth Largest Element In a Stream | Link | Easy | YouTube | N/A | N/A | N/A | |
| 1046 | Last Stone Weight | Link | Easy | YouTube | Typescript | N/A | N/A | |
| N/A | K Closest Points to Origin | Link | Medium | YouTube | N/A | N/A | N/A | |
| 0215 | Kth Largest Element In An Array | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0621 | Task Scheduler | Link | Medium | YouTube | Typescript | N/A | N/A | |
| N/A | Design Twitter | Link | Medium | YouTube | N/A | N/A | N/A | |
| 0295 | Find Median From Data Stream - [Blind] | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Intro to Graphs - Data Structures & Algorithms for Beginners
◽ - Matrix DFS - Data Structures & Algorithms for Beginners
◽ - Matrix BFS - Data Structures & Algorithms for Beginners
◽ - Adjacency List - Data Structures & Algorithms for Beginners
◽ - 1-Dimension DP - Data Structures & Algorithms for Beginners
◽ - Palindromes - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0070 | Climbing Stairs - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0746 | Min Cost Climbing Stairs | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0198 | House Robber - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0213 | House Robber II - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0005 | Longest Palindromic Substring - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0647 | Palindromic Substrings - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0091 | Decode Ways - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0322 | Coin Change - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0152 | Maximum Product Subarray - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0139 | Word Break - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0300 | Longest Increasing Subsequence - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| N/A | Partition Equal Subset Sum | Link | Medium | YouTube | N/A | N/A | N/A |
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0057 | Insert Interval - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0056 | Merge Intervals - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0435 | Non Overlapping Intervals - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0252 | Meeting Rooms - [Blind] | Link | Easy | YouTube | N/A | N/A | N/A | 📘 |
| 0253 | Meeting Rooms II - [Blind] | Link | Medium | YouTube | N/A | N/A | N/A | 📘 |
| N/A | Minimum Interval to Include Each Query | Link | Hard | YouTube | N/A | N/A | N/A |
◽ - Kadane's Algorithm - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0053 | Maximum Subarray - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0055 | Jump Game - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0045 | Jump Game II | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0134 | Gas Station | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0846 | Hand of Straights | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 1899 | Merge Triplets to Form Target Triplet | Link | Medium | YouTube | Typescript | N/A | N/A | |
| N/A | Partition Labels | Link | Medium | YouTube | N/A | N/A | N/A | |
| 0678 | Valid Parenthesis String | Link | Medium | YouTube | Typescript | N/A | N/A |
◽ - Dijkstra's - Advanced Algorithms
◽ - Prim's - Advanced Algorithms
◽ - Kruskal's - Advanced Algorithms
◽ - Topological Sort - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| N/A | Reconstruct Itinerary | Link | Hard | YouTube | N/A | N/A | N/A | |
| N/A | Min Cost to Connect All Points | Link | Medium | YouTube | N/A | N/A | N/A | |
| N/A | Network Delay Time | Link | Medium | YouTube | N/A | N/A | N/A | |
| N/A | Swim In Rising Water | Link | Hard | YouTube | N/A | N/A | N/A | |
| 0269 | Alien Dictionary - [Blind] | Link | Hard | YouTube | N/A | N/A | N/A | |
| 0787 | Cheapest Flights Within K Stops | Link | Medium | YouTube | Typescript | N/A | N/A |
◽ - 2-Dimension DP - Data Structures & Algorithms for Beginners
◽ - 0 / 1 Knapsack - Advanced Algorithms
◽ - Unbounded Knapsack - Advanced Algorithms
◽ - LCS - Advanced Algorithms
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0062 | Unique Paths - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 1143 | Longest Common Subsequence - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0309 | Best Time to Buy And Sell Stock With Cooldown | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0518 | Coin Change II | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0494 | Target Sum | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0097 | Interleaving String | Link | Medium | YouTube | Typescript | N/A | N/A | |
| N/A | Longest Increasing Path In a Matrix | Link | Hard | YouTube | N/A | N/A | N/A | |
| 0115 | Distinct Subsequences | Link | Hard | YouTube | Typescript | N/A | N/A | |
| N/A | Edit Distance | Link | Medium | YouTube | N/A | N/A | N/A | |
| 0312 | Burst Balloons | Link | Hard | YouTube | Typescript | N/A | N/A | |
| 0010 | Regular Expression Matching | Link | Hard | YouTube | Typescript | N/A | N/A |
◽ - Bit Operations - Data Structures & Algorithms for Beginners
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0136 | Single Number | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0191 | Number of 1 Bits - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0338 | Counting Bits - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0190 | Reverse Bits - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0268 | Missing Number - [Blind] | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0371 | Sum of Two Integers - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0007 | Reverse Integer | Link | Medium | YouTube | Typescript | N/A | N/A |
| # | Title - NeetCode | LeetCode | Difficulty | Video Solution | Code Solution | Time | Space | Anki |
|---|---|---|---|---|---|---|---|---|
| 0048 | Rotate Image - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0054 | Spiral Matrix - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | 📘 |
| 0073 | Set Matrix Zeroes - [Blind] | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0202 | Happy Number | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0066 | Plus One | Link | Easy | YouTube | Typescript | N/A | N/A | |
| 0050 | Pow(x, n) | Link | Medium | YouTube | Typescript | N/A | N/A | |
| 0043 | Multiply Strings | Link | Medium | YouTube | Typescript | N/A | N/A | |
| N/A | Detect Squares | Link | Medium | YouTube | N/A | N/A | N/A |