Master DSA Patterns
Practice curated LeetCode problems organized by patterns.
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Easy0 / 48
Medium0 / 196
Hard0 / 56
Progress: 0 / 10
Easy
Easy
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Move Zeroes | Easy | |||||
| Majority Element | Easy | |||||
| Remove Duplicates from Sorted Array | Easy | |||||
| Best Time to Buy and Sell Stock | Easy | |||||
| Rotate Array | Medium | |||||
| Product of Array Except Self | Medium | |||||
| Best Time to Buy and Sell Stock II | Medium | |||||
| Number of Zero-Filled Subarrays | Medium | |||||
| Increasing Triplet Subsequence | Medium | |||||
| First Missing Positive | Hard |
Progress: 0 / 6
Easy
Easy
Medium
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Is Subsequence | Easy | |||||
| Valid Palindrome | Easy | |||||
| Longest Common Prefix | Easy | |||||
| Zigzag Conversion | Medium | |||||
| Reverse Words in a String | Medium | |||||
| Guess the Word | Hard |
Progress: 0 / 7
Easy
Easy
Easy
Easy
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Single Number | Easy | |||||
| Number of 1 Bits | Easy | |||||
| Counting Bits | Easy | |||||
| Reverse Bits | Easy | |||||
| Bitwise AND of Numbers Range | Medium | |||||
| Single Number III | Medium | |||||
| Sum of Two Integers | Medium |
Progress: 0 / 13
Easy
Easy
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Design HashMap | Easy | |||||
| Maximum Number of Balloons | Easy | |||||
| Number of Good Pairs | Easy | |||||
| Isomorphic Strings | Easy | |||||
| Ransom Note | Easy | |||||
| Contains Duplicate II | Easy | |||||
| Group Anagrams | Medium | |||||
| Encode and Decode TinyURL | Medium | |||||
| Reorganize String | Medium | |||||
| Longest Consecutive Sequence | Medium | |||||
| Split Array into Consecutive Subsequences | Medium | |||||
| Number of Matching Subsequences | Medium | |||||
| Number of Good Ways to Split a String | Medium |
Progress: 0 / 5
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Merge Sorted Array | Easy | |||||
| Two Sum II - Input Array Is Sorted | Medium | |||||
| Container With Most Water | Medium | |||||
| 3Sum | Medium | |||||
| Trapping Rain Water | Hard |
Progress: 0 / 5
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Range Sum Query - Immutable | Easy | |||||
| Subarray Sum Equals K | Medium | |||||
| Subarray Sums Divisible by K | Medium | |||||
| Continuous Subarray Sum | Medium | |||||
| Contiguous Array | Medium |
Progress: 0 / 5
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Maximum Average Subarray I | Easy | |||||
| Find All Anagrams in a String | Medium | |||||
| Permutation in String | Medium | |||||
| Maximum Sum of Distinct Subarrays With Length K | Medium | |||||
| Substring with Concatenation of All Words | Hard |
Progress: 0 / 5
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Longest Substring Without Repeating Characters | Medium | |||||
| Longest Repeating Character Replacement | Medium | |||||
| Minimum Size Subarray Sum | Medium | |||||
| Max Consecutive Ones III | Medium | |||||
| Minimum Window Substring | Hard |
Progress: 0 / 4
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Maximum Subarray | Medium | |||||
| Maximum Sum Circular Subarray | Medium | |||||
| Maximum Product Subarray | Medium | |||||
| Best Sightseeing Pair | Medium |
Progress: 0 / 5
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Spiral Matrix | Medium | |||||
| Rotate Image | Medium | |||||
| Set Matrix Zeroes | Medium | |||||
| Valid Sudoku | Medium | |||||
| Game of Life | Medium |
Progress: 0 / 10
Medium
Medium
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Intersection of Two Linked Lists | Easy | |||||
| Design Linked List | Medium | |||||
| Remove Nth Node From End of List | Medium | |||||
| Remove Duplicates from Sorted List II | Medium | |||||
| Swap Nodes in Pairs | Medium | |||||
| Copy List with Random Pointer | Medium | |||||
| Partition List | Medium | |||||
| Rotate List | Medium | |||||
| Add Two Numbers | Medium | |||||
| Flatten a Multilevel Doubly Linked List | Medium |
Progress: 0 / 4
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Palindrome Linked List | Easy | |||||
| Reverse Linked List | Easy | |||||
| Reverse Linked List II | Medium | |||||
| Reverse Nodes in k-Group | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Middle of the Linked List | Easy | |||||
| Happy Number | Easy | |||||
| Linked List Cycle II | Medium |
Progress: 0 / 8
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Valid Parentheses | Easy | |||||
| Remove All Adjacent Duplicates In String | Easy | |||||
| Min Stack | Medium | |||||
| Remove Duplicate Letters | Medium | |||||
| Removing Stars From a String | Medium | |||||
| Evaluate Reverse Polish Notation | Medium | |||||
| Basic Calculator II | Medium | |||||
| Longest Valid Parentheses | Hard |
Progress: 0 / 6
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Next Greater Element I | Easy | |||||
| Daily Temperatures | Medium | |||||
| Online Stock Span | Medium | |||||
| 132 Pattern | Medium | |||||
| Number of Visible People in a Queue | Hard | |||||
| Largest Rectangle in Histogram | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Number of Recent Calls | Easy | |||||
| Time Needed to Buy Tickets | Easy | |||||
| Reveal Cards In Increasing Order | Medium |
Progress: 0 / 4
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit | Medium | |||||
| Jump Game VI | Medium | |||||
| Sliding Window Maximum | Hard | |||||
| Max Value of Equation | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Sort Characters By Frequency | Medium | |||||
| Top K Frequent Words | Medium | |||||
| Maximum Gap | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Merge Two Sorted Lists | Easy | |||||
| Pow(x, n) | Medium | |||||
| Decode String | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Convert Sorted List to Binary Search Tree | Medium | |||||
| Construct Quad Tree | Medium | |||||
| Maximum Binary Tree | Medium |
Progress: 0 / 2
Medium
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Sort List | Medium | |||||
| Reverse Pairs | Hard |
Progress: 0 / 2
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Sort Colors | Medium | |||||
| Kth Largest Element in an Array | Medium |
Progress: 0 / 10
Medium
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Search Insert Position | Easy | |||||
| Find First and Last Position of Element in Sorted Array | Medium | |||||
| Search in Rotated Sorted Array | Medium | |||||
| Find Peak Element | Medium | |||||
| Random Pick with Weight | Medium | |||||
| Koko Eating Bananas | Medium | |||||
| Find Minimum in Rotated Sorted Array | Medium | |||||
| Search a 2D Matrix | Medium | |||||
| Find in Mountain Array | Hard | |||||
| Median of Two Sorted Arrays | Hard |
Progress: 0 / 8
Medium
Medium
Medium
Medium
Medium
Medium
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Generate Parentheses | Medium | |||||
| Permutations | Medium | |||||
| Subsets | Medium | |||||
| Combination Sum | Medium | |||||
| Combination Sum II | Medium | |||||
| Letter Combinations of a Phone Number | Medium | |||||
| Palindrome Partitioning | Medium | |||||
| N-Queens | Hard |
Progress: 0 / 5
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Binary Tree Level Order Traversal | Medium | |||||
| Binary Tree Right Side View | Medium | |||||
| Binary Tree Zigzag Level Order Traversal | Medium | |||||
| Populating Next Right Pointers in Each Node II | Medium | |||||
| Maximum Width of Binary Tree | Medium |
Tree Traversal - Pre Order
Progress: 0 / 11
Easy
Easy
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Binary Tree Preorder Traversal | Easy | |||||
| Same Tree | Easy | |||||
| Symmetric Tree | Easy | |||||
| Binary Tree Paths | Easy | |||||
| Convert Sorted Array to Binary Search Tree | Easy | |||||
| Count Complete Tree Nodes | Easy | |||||
| Path Sum III | Medium | |||||
| Maximum Difference Between Node and Ancestor | Medium | |||||
| Construct Binary Tree from Preorder and Inorder Traversal | Medium | |||||
| Construct Binary Tree from Inorder and Postorder Traversal | Medium | |||||
| Serialize and Deserialize Binary Tree | Hard |
Progress: 0 / 6
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Binary Tree Inorder Traversal | Easy | |||||
| Minimum Distance Between BST Nodes | Easy | |||||
| Minimum Absolute Difference in BST | Easy | |||||
| Validate Binary Search Tree | Medium | |||||
| Kth Smallest Element in a BST | Medium | |||||
| Binary Search Tree Iterator | Medium |
Tree Traversal - Post-Order
Progress: 0 / 9
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Binary Tree Postorder Traversal | Easy | |||||
| Invert Binary Tree | Easy | |||||
| Diameter of Binary Tree | Easy | |||||
| Delete Nodes And Return Forest | Medium | |||||
| Lowest Common Ancestor of a Binary Tree | Medium | |||||
| Find Duplicate Subtrees | Medium | |||||
| Flatten Binary Tree to Linked List | Medium | |||||
| Distribute Coins in Binary Tree | Medium | |||||
| Binary Tree Maximum Path Sum | Hard |
Progress: 0 / 4
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Trim a Binary Search Tree | Medium | |||||
| My Calendar I | Medium | |||||
| My Calendar II | Medium | |||||
| Stock Price Fluctuation | Medium |
Progress: 0 / 6
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Implement Trie (Prefix Tree) | Medium | |||||
| Design Add and Search Words Data Structure | Medium | |||||
| Search Suggestions System | Medium | |||||
| Longest Word in Dictionary | Medium | |||||
| Maximum XOR of Two Numbers in an Array | Medium | |||||
| Word Search II | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Furthest Building You Can Reach | Medium | |||||
| Single-Threaded CPU | Medium | |||||
| Process Tasks Using Servers | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Find Median from Data Stream | Hard | |||||
| IPO | Hard | |||||
| Sliding Window Median | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Kth Largest Element in a Stream | Easy | |||||
| Top K Frequent Elements | Medium | |||||
| K Closest Points to Origin | Medium |
Progress: 0 / 5
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Merge Intervals | Medium | |||||
| Insert Interval | Medium | |||||
| Minimum Number of Arrows to Burst Balloons | Medium | |||||
| Maximum Number of Events That Can Be Attended | Medium | |||||
| Non-overlapping Intervals | Medium |
K-Way Merge
Progress: 0 / 4
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Find K Pairs with Smallest Sums | Medium | |||||
| Kth Smallest Element in a Sorted Matrix | Medium | |||||
| Merge k Sorted Lists | Hard | |||||
| Smallest Range Covering Elements from K Lists | Hard |
Data Structure Design
Progress: 0 / 8
Medium
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Design Browser History | Medium | |||||
| Time Based Key-Value Store | Medium | |||||
| Snapshot Array | Medium | |||||
| Design Twitter | Medium | |||||
| LRU Cache | Medium | |||||
| Insert Delete GetRandom O(1) | Medium | |||||
| Design a Food Rating System | Medium | |||||
| Maximum Frequency Stack | Hard |
Progress: 0 / 7
Medium
Medium
Medium
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Jump Game II | Medium | |||||
| Minimum Add to Make Parentheses Valid | Medium | |||||
| Gas Station | Medium | |||||
| Task Scheduler | Medium | |||||
| Minimum Cost to Hire K Workers | Hard | |||||
| Candy | Hard | |||||
| Minimum Number of Refueling Stops | Hard |
Progress: 0 / 10
Medium
Medium
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Number of Islands | Medium | |||||
| Time Needed to Inform All Employees | Medium | |||||
| All Paths From Source to Target | Medium | |||||
| Clone Graph | Medium | |||||
| Is Graph Bipartite? | Medium | |||||
| All Nodes Distance K in Binary Tree | Medium | |||||
| Employee Importance | Medium | |||||
| Surrounded Regions | Medium | |||||
| Pacific Atlantic Water Flow | Medium | |||||
| Making A Large Island | Hard |
Progress: 0 / 6
Medium
Medium
Medium
Hard
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Rotting Oranges | Medium | |||||
| 01 Matrix | Medium | |||||
| Open the Lock | Medium | |||||
| Shortest Path in a Grid with Obstacles Elimination | Hard | |||||
| Bus Routes | Hard | |||||
| Word Ladder | Hard |
Progress: 0 / 4
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Course Schedule II | Medium | |||||
| Find Eventual Safe States | Medium | |||||
| Minimum Height Trees | Medium | |||||
| Sort Items by Groups Respecting Dependencies | Hard |
Progress: 0 / 4
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Number of Provinces | Medium | |||||
| Redundant Connection | Medium | |||||
| Accounts Merge | Medium | |||||
| Minimize Malware Spread | Hard |
Progress: 0 / 1
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Min Cost to Connect All Points | Medium |
Progress: 0 / 5
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Network Delay Time | Medium | |||||
| Cheapest Flights Within K Stops | Medium | |||||
| Path with Maximum Probability | Medium | |||||
| Path With Minimum Effort | Medium | |||||
| Swim in Rising Water | Hard |
Eulerian Circuit
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Reconstruct Itinerary | Hard | |||||
| Cracking the Safe | Hard |
Progress: 0 / 4
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Climbing Stairs | Easy | |||||
| Min Cost Climbing Stairs | Easy | |||||
| House Robber | Medium | |||||
| House Robber II | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Partition Equal Subset Sum | Medium | |||||
| Target Sum | Medium | |||||
| Last Stone Weight II | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Coin Change | Medium | |||||
| Coin Change II | Medium | |||||
| Perfect Squares | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Longest Increasing Subsequence | Medium | |||||
| Number of Longest Increasing Subsequence | Medium | |||||
| Russian Doll Envelopes | Hard |
Progress: 0 / 9
Medium
Medium
Medium
Hard
Hard
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Unique Paths II | Medium | |||||
| Minimum Path Sum | Medium | |||||
| Triangle | Medium | |||||
| Count Square Submatrices with All Ones | Medium | |||||
| Maximum Number of Points with Cost | Medium | |||||
| Burst Balloons | Hard | |||||
| Maximum Profit in Job Scheduling | Hard | |||||
| Cherry Pickup | Hard | |||||
| Longest Increasing Path in a Matrix | Hard |
String DP
Progress: 0 / 9
Medium
Medium
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Longest Common Subsequence | Medium | |||||
| Edit Distance | Medium | |||||
| Longest Palindromic Subsequence | Medium | |||||
| Decode Ways | Medium | |||||
| Word Break | Medium | |||||
| Interleaving String | Medium | |||||
| Wildcard Matching | Hard | |||||
| Distinct Subsequences | Hard | |||||
| Palindrome Partitioning II | Hard |
Tree / Graph DP
Progress: 0 / 5
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| House Robber III | Medium | |||||
| Unique Binary Search Trees II | Medium | |||||
| Number of Ways to Arrive at Destination | Medium | |||||
| Binary Tree Cameras | Hard | |||||
| Sum of Distances in Tree | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Minimum Number of Work Sessions to Finish the Tasks | Medium | |||||
| Fair Distribution of Cookies | Medium | |||||
| Shortest Path Visiting All Nodes | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Count Numbers with Unique Digits | Medium | |||||
| Number of Digit One | Hard | |||||
| Numbers At Most N Given Digit Set | Hard |
Probability DP
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Knight Probability in Chessboard | Medium | |||||
| Soup Servings | Medium | |||||
| New 21 Game | Medium |
State Machine DP
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Best Time to Buy and Sell Stock with Cooldown | Medium | |||||
| Best Time to Buy and Sell Stock III | Hard |
Progress: 0 / 2
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Repeated String Match | Medium | |||||
| Shortest Palindrome | Hard |
Binary Indexed Tree / Segment Tree
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Range Sum Query - Mutable | Medium | |||||
| Count of Smaller Numbers After Self | Hard |
Maths / Geometry
Progress: 0 / 6
Medium
Medium
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Palindrome Number | Easy | |||||
| Reverse Integer | Medium | |||||
| Factorial Trailing Zeroes | Medium | |||||
| Valid Square | Medium | |||||
| Minimum Area Rectangle II | Medium | |||||
| Max Points on a Line | Hard |
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Minimum Interval to Include Each Query | Hard | |||||
| The Skyline Problem | Hard |
Progress: 0 / 1
| Status | Problem | Difficulty | Solution | Animation | Notes | Star |
|---|---|---|---|---|---|---|
| Longest Duplicate Substring | Hard |