Master DSA Patterns
Practice curated LeetCode problems organized by patterns.
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Hard0 / 56
Progress: 0 / 10
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Spiral Matrix | Medium | ||||
| Rotate Image | Medium | ||||
| Set Matrix Zeroes | Medium | ||||
| Valid Sudoku | Medium | ||||
| Game of Life | Medium |
Progress: 0 / 10
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Middle of the Linked List | Easy | ||||
| Happy Number | Easy | ||||
| Linked List Cycle II | Medium |
Progress: 0 / 8
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Number of Recent Calls | Easy | ||||
| Time Needed to Buy Tickets | Easy | ||||
| Reveal Cards In Increasing Order | Medium |
Progress: 0 / 4
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Sort Characters By Frequency | Medium | ||||
| Top K Frequent Words | Medium | ||||
| Maximum Gap | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Merge Two Sorted Lists | Easy | ||||
| Pow(x, n) | Medium | ||||
| Decode String | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Convert Sorted List to Binary Search Tree | Medium | ||||
| Construct Quad Tree | Medium | ||||
| Maximum Binary Tree | Medium |
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Sort List | Medium | ||||
| Reverse Pairs | Hard |
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Sort Colors | Medium | ||||
| Kth Largest Element in an Array | Medium |
Progress: 0 / 10
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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 | 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
| Status | Problem | Difficulty | Solution | 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 | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Trim a Binary Search Tree | Medium | ||||
| My Calendar I | Medium | ||||
| My Calendar II | Medium | ||||
| Stock Price Fluctuation | Medium |
Progress: 0 / 6
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Furthest Building You Can Reach | Medium | ||||
| Single-Threaded CPU | Medium | ||||
| Process Tasks Using Servers | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Find Median from Data Stream | Hard | ||||
| IPO | Hard | ||||
| Sliding Window Median | Hard |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Kth Largest Element in a Stream | Easy | ||||
| Top K Frequent Elements | Medium | ||||
| K Closest Points to Origin | Medium |
Progress: 0 / 5
| Status | Problem | Difficulty | Solution | 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 | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Number of Provinces | Medium | ||||
| Redundant Connection | Medium | ||||
| Accounts Merge | Medium | ||||
| Minimize Malware Spread | Hard |
Progress: 0 / 1
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Min Cost to Connect All Points | Medium |
Progress: 0 / 5
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Reconstruct Itinerary | Hard | ||||
| Cracking the Safe | Hard |
Progress: 0 / 4
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Climbing Stairs | Easy | ||||
| Min Cost Climbing Stairs | Easy | ||||
| House Robber | Medium | ||||
| House Robber II | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Partition Equal Subset Sum | Medium | ||||
| Target Sum | Medium | ||||
| Last Stone Weight II | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Coin Change | Medium | ||||
| Coin Change II | Medium | ||||
| Perfect Squares | Medium |
Progress: 0 / 3
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Longest Increasing Subsequence | Medium | ||||
| Number of Longest Increasing Subsequence | Medium | ||||
| Russian Doll Envelopes | Hard |
Progress: 0 / 9
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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
| Status | Problem | Difficulty | Solution | 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 | 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 | 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 | Notes | Star |
|---|---|---|---|---|---|
| Knight Probability in Chessboard | Medium | ||||
| Soup Servings | Medium | ||||
| New 21 Game | Medium |
State Machine DP
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Best Time to Buy and Sell Stock with Cooldown | Medium | ||||
| Best Time to Buy and Sell Stock III | Hard |
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Repeated String Match | Medium | ||||
| Shortest Palindrome | Hard |
Binary Indexed Tree / Segment Tree
Progress: 0 / 2
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Range Sum Query - Mutable | Medium | ||||
| Count of Smaller Numbers After Self | Hard |
Maths / Geometry
Progress: 0 / 6
| Status | Problem | Difficulty | Solution | 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 | Notes | Star |
|---|---|---|---|---|---|
| Minimum Interval to Include Each Query | Hard | ||||
| The Skyline Problem | Hard |
Progress: 0 / 1
| Status | Problem | Difficulty | Solution | Notes | Star |
|---|---|---|---|---|---|
| Longest Duplicate Substring | Hard |