Enhanced Study Strategy:
- 2 problems per day for 125 days (both from the same category when possible)
- ALL 250 problems included with no gaps
- Spaced repetition: Categories cycle with intelligent spacing to optimize retention
- Progressive difficulty: Early days focus on Easy, gradually increasing complexity
- Category focus: Daily concentration on single topics for deeper pattern recognition
- Intelligent timing: Easier categories appear earlier, advanced topics later in the plan
Topic: Arrays & Hashing
Problems:
- 🟢 Concatenation of Array - Arrays & Hashing
- 🟡 Group Anagrams - Arrays & Hashing
Topic: Binary Search
Problems:
- 🟢 Binary Search - Binary Search
- 🟢 Search Insert Position - Binary Search
Topic: 1-D Dynamic Programming
Problems:
- 🟢 Climbing Stairs - 1-D Dynamic Programming
- 🟢 Min Cost Climbing Stairs - 1-D Dynamic Programming
Topic: Binary Search
Problems:
- 🟢 Guess Number Higher Or Lower - Binary Search
- 🟡 Search a 2D Matrix - Binary Search
Topic: Heap / Priority Queue
Problems:
- 🟢 Kth Largest Element In a Stream - Heap / Priority Queue
- 🟢 Last Stone Weight - Heap / Priority Queue
Topic: Advanced Graphs
Problems:
- 🟡 Path with Minimum Effort - Advanced Graphs
- 🟡 Network Delay Time - Advanced Graphs
Topic: Two Pointers
Problems:
- 🟢 Reverse String - Two Pointers
- 🟡 Two Sum II Input Array Is Sorted - Two Pointers
Topic: Backtracking
Problems:
- 🟢 Sum of All Subsets XOR Total - Backtracking
- 🟡 Subsets - Backtracking
Topic: Heap / Priority Queue
Problems:
- 🟡 K Closest Points to Origin - Heap / Priority Queue
- 🟡 Kth Largest Element In An Array - Heap / Priority Queue
Topic: Arrays & Hashing
Problems:
- 🟢 Contains Duplicate - Arrays & Hashing
- 🟡 Sort an Array - Arrays & Hashing
Topic: Arrays & Hashing
Problems:
- 🟢 Valid Anagram - Arrays & Hashing
- 🟢 Two Sum - Arrays & Hashing
Topic: Advanced Graphs
Problems:
- 🟡 Min Cost to Connect All Points - Advanced Graphs
- 🟡 Cheapest Flights Within K Stops - Advanced Graphs
Topic: Linked List
Problems:
- 🟢 Reverse Linked List - Linked List
- 🟡 Reorder List - Linked List
Topic: Linked List
Problems:
- 🟢 Merge Two Sorted Lists - Linked List
- 🟢 Linked List Cycle - Linked List
Topic: Stack
Problems:
- 🟢 Baseball Game - Stack
- 🟢 Valid Parentheses - Stack
Topic: Trees
Problems:
- 🟢 Binary Tree Inorder Traversal - Trees
- 🟡 Lowest Common Ancestor of a Binary Search Tree - Trees
Topic: Stack
Problems:
- 🟢 Implement Stack Using Queues - Stack
- 🟢 Implement Queue using Stacks - Stack
Topic: Backtracking
Problems:
- 🟡 Combination Sum - Backtracking
- 🟡 Combination Sum II - Backtracking
Topic: Heap / Priority Queue
Problems:
- 🟡 Task Scheduler - Heap / Priority Queue
- 🟡 Design Twitter - Heap / Priority Queue
Topic: Sliding Window
Problems:
- 🟢 Contains Duplicate II - Sliding Window
- 🟢 Best Time to Buy And Sell Stock - Sliding Window
Topic: Intervals
Problems:
- 🟢 Meeting Rooms - Intervals
- 🟡 Insert Interval - Intervals
Topic: Graphs
Problems:
- 🟢 Island Perimeter - Graphs
- 🟡 Number of Islands - Graphs
Topic: Linked List
Problems:
- 🟡 Remove Nth Node From End of List - Linked List
- 🟡 Copy List With Random Pointer - Linked List
Topic: Arrays & Hashing
Problems:
- 🟢 Longest Common Prefix - Arrays & Hashing
- 🟢 Remove Element - Arrays & Hashing
Topic: Two Pointers
Problems:
- 🟢 Valid Palindrome - Two Pointers
- 🟡 3Sum - Two Pointers
Topic: Binary Search
Problems:
- 🟢 Sqrt(x) - Binary Search
- 🟡 Koko Eating Bananas - Binary Search
Topic: Heap / Priority Queue
Problems:
- 🟡 Single Threaded CPU - Heap / Priority Queue
- 🟡 Reorganize String - Heap / Priority Queue
Topic: Arrays & Hashing
Problems:
- 🟢 Majority Element - Arrays & Hashing
- 🟡 Sort Colors - Arrays & Hashing
Topic: Stack
Problems:
- 🟡 Min Stack - Stack
- 🟡 Evaluate Reverse Polish Notation - Stack
Topic: Backtracking
Problems:
- 🟡 Combinations - Backtracking
- 🟡 Permutations - Backtracking
Topic: Two Pointers
Problems:
- 🟢 Valid Palindrome II - Two Pointers
- 🟡 4Sum - Two Pointers
Topic: Linked List
Problems:
- 🟡 Add Two Numbers - Linked List
- 🟡 Find The Duplicate Number - Linked List
Topic: Advanced Graphs
Problems:
- 🔴 Reconstruct Itinerary - Advanced Graphs
- 🔴 Swim In Rising Water - Advanced Graphs
Topic: Tries
Problems:
- 🟡 Implement Trie Prefix Tree - Tries
- 🟡 Design Add And Search Words Data Structure - Tries
Topic: 1-D Dynamic Programming
Problems:
- 🟢 N-th Tribonacci Number - 1-D Dynamic Programming
- 🟡 House Robber - 1-D Dynamic Programming
Topic: Stack
Problems:
- 🟡 Generate Parentheses - Stack
- 🟡 Asteroid Collision - Stack
Topic: 2-D Dynamic Programming
Problems:
- 🟡 Unique Paths - 2-D Dynamic Programming
- 🟡 Unique Paths II - 2-D Dynamic Programming
Topic: Graphs
Problems:
- 🟢 Verifying An Alien Dictionary - Graphs
- 🟡 Max Area of Island - Graphs
Topic: Advanced Graphs
Problems:
- 🔴 Alien Dictionary - Advanced Graphs
- 🔴 Find Critical and Pseudo Critical Edges in Minimum Spanning Tree - Advanced Graphs
Topic: Intervals
Problems:
- 🟡 Merge Intervals - Intervals
- 🟡 Non Overlapping Intervals - Intervals
Topic: Two Pointers
Problems:
- 🟢 Merge Strings Alternately - Two Pointers
- 🟡 Rotate Array - Two Pointers
Topic: Tries
Problems:
- 🟡 Extra Characters in a String - Tries
- 🔴 Word Search II - Tries
Topic: Stack
Problems:
- 🟡 Daily Temperatures - Stack
- 🟡 Online Stock Span - Stack
Topic: Linked List
Problems:
- 🟡 Reverse Linked List II - Linked List
- 🟡 Design Circular Queue - Linked List
Topic: Arrays & Hashing
Problems:
- 🟢 Design HashSet - Arrays & Hashing
- 🟡 Top K Frequent Elements - Arrays & Hashing
Topic: Advanced Graphs
Problems:
- 🔴 Build a Matrix With Conditions - Advanced Graphs
- 🔴 Greatest Common Divisor Traversal - Advanced Graphs
Topic: Intervals
Problems:
- 🟡 Meeting Rooms II - Intervals
- 🔴 Meeting Rooms III - Intervals
Topic: Sliding Window
Problems:
- 🟡 Longest Substring Without Repeating Characters - Sliding Window
- 🟡 Longest Repeating Character Replacement - Sliding Window
Topic: Greedy
Problems:
- 🟢 Lemonade Change - Greedy
- 🟡 Maximum Subarray - Greedy
Topic: Graphs
Problems:
- 🟢 Find the Town Judge - Graphs
- 🟡 Clone Graph - Graphs
Topic: Bit Manipulation
Problems:
- 🟢 Single Number - Bit Manipulation
- 🟡 Sum of Two Integers - Bit Manipulation
Topic: Math & Geometry
Problems:
- 🟢 Excel Sheet Column Title - Math & Geometry
- 🟡 Insert Greatest Common Divisors in Linked List - Math & Geometry
Topic: Graphs
Problems:
- 🟡 Walls And Gates - Graphs
- 🟡 Rotting Oranges - Graphs
Topic: Backtracking
Problems:
- 🟡 Subsets II - Backtracking
- 🟡 Permutations II - Backtracking
Topic: Linked List
Problems:
Topic: 1-D Dynamic Programming
Problems:
- 🟡 House Robber II - 1-D Dynamic Programming
- 🟡 Longest Palindromic Substring - 1-D Dynamic Programming
Topic: 2-D Dynamic Programming
Problems:
- 🟡 Minimum Path Sum - 2-D Dynamic Programming
- 🟡 Longest Common Subsequence - 2-D Dynamic Programming
Topic: Math & Geometry
Problems:
- 🟢 Greatest Common Divisor of Strings - Math & Geometry
- 🟡 Rotate Image - Math & Geometry
Topic: Arrays & Hashing
Problems:
- 🟢 Design HashMap - Arrays & Hashing
- 🟡 Encode and Decode Strings - Arrays & Hashing
Topic: Sliding Window
Problems:
- 🟡 Permutation In String - Sliding Window
- 🟡 Minimum Size Subarray Sum - Sliding Window
Topic: Two Pointers
Problems:
- 🟢 Merge Sorted Array - Two Pointers
- 🟡 Container With Most Water - Two Pointers
Topic: Two Pointers
Problems:
- 🟢 Remove Duplicates From Sorted Array - Two Pointers
- 🟡 Boats to Save People - Two Pointers
Topic: Greedy
Problems:
- 🟡 Maximum Sum Circular Subarray - Greedy
- 🟡 Longest Turbulent Subarray - Greedy
Topic: Heap / Priority Queue
Problems:
- 🟡 Longest Happy String - Heap / Priority Queue
- 🟡 Car Pooling - Heap / Priority Queue
Topic: Trees
Problems:
- 🟢 Binary Tree Preorder Traversal - Trees
- 🟡 Insert into a Binary Search Tree - Trees
Topic: Graphs
Problems:
- 🟡 Pacific Atlantic Water Flow - Graphs
- 🟡 Surrounded Regions - Graphs
Topic: Bit Manipulation
Problems:
- 🟢 Number of 1 Bits - Bit Manipulation
- 🟡 Reverse Integer - Bit Manipulation
Topic: 1-D Dynamic Programming
Problems:
- 🟡 Palindromic Substrings - 1-D Dynamic Programming
- 🟡 Decode Ways - 1-D Dynamic Programming
Topic: Math & Geometry
Problems:
- 🟢 Transpose Matrix - Math & Geometry
- 🟡 Spiral Matrix - Math & Geometry
Topic: Greedy
Problems:
- 🟡 Jump Game - Greedy
- 🟡 Jump Game II - Greedy
Topic: Bit Manipulation
Problems:
- 🟢 Counting Bits - Bit Manipulation
- 🟡 Bitwise AND of Numbers Range - Bit Manipulation
Topic: Stack
Problems:
- 🟡 Car Fleet - Stack
- 🟡 Simplify Path - Stack
Topic: Math & Geometry
Problems:
- 🟢 Happy Number - Math & Geometry
- 🟡 Set Matrix Zeroes - Math & Geometry
Topic: Bit Manipulation
Problems:
- 🟢 Add Binary - Bit Manipulation
- 🟡 Minimum Array End - Bit Manipulation
Topic: Arrays & Hashing
Problems:
- 🟡 Range Sum Query 2D Immutable - Arrays & Hashing
- 🟡 Product of Array Except Self - Arrays & Hashing
Topic: Stack
Problems:
- 🟡 Decode String - Stack
- 🔴 Maximum Frequency Stack - Stack
Topic: Graphs
Problems:
- 🟡 Open The Lock - Graphs
- 🟡 Course Schedule - Graphs
Topic: Trees
Problems:
- 🟢 Binary Tree Postorder Traversal - Trees
- 🟡 Delete Node in a BST - Trees
Topic: Math & Geometry
Problems:
Topic: Binary Search
Problems:
- 🟡 Capacity to Ship Packages Within D Days - Binary Search
- 🟡 Find Minimum In Rotated Sorted Array - Binary Search
Topic: Heap / Priority Queue
Problems:
- 🔴 Find Median From Data Stream - Heap / Priority Queue
- 🔴 IPO - Heap / Priority Queue
Topic: Trees
Problems:
- 🟡 Binary Tree Level Order Traversal - Trees
- 🟡 Binary Tree Right Side View - Trees
Topic: Bit Manipulation
Problems:
- 🟢 Reverse Bits - Bit Manipulation
- 🟢 Missing Number - Bit Manipulation
Topic: Arrays & Hashing
Problems:
- 🟡 Valid Sudoku - Arrays & Hashing
- 🟡 Longest Consecutive Sequence - Arrays & Hashing
Topic: Greedy
Problems:
- 🟡 Jump Game VII - Greedy
- 🟡 Gas Station - Greedy
Topic: Trees
Problems:
- 🟡 Construct Quad Tree - Trees
- 🟡 Count Good Nodes In Binary Tree - Trees
Topic: Backtracking
Problems:
- 🟡 Word Search - Backtracking
- 🟡 Palindrome Partitioning - Backtracking
Topic: Greedy
Problems:
- 🟡 Hand of Straights - Greedy
- 🟡 Dota2 Senate - Greedy
Topic: Binary Search
Problems:
- 🟡 Search In Rotated Sorted Array - Binary Search
- 🟡 Search In Rotated Sorted Array II - Binary Search
Topic: Trees
Problems:
- 🟡 Validate Binary Search Tree - Trees
- 🟡 Kth Smallest Element In a Bst - Trees
Topic: Linked List
Problems:
- 🔴 Merge K Sorted Lists - Linked List
- 🔴 Reverse Nodes In K Group - Linked List
Topic: 1-D Dynamic Programming
Problems:
- 🟡 Coin Change - 1-D Dynamic Programming
- 🟡 Maximum Product Subarray - 1-D Dynamic Programming
Topic: Arrays & Hashing
Problems:
- 🟡 Best Time to Buy And Sell Stock II - Arrays & Hashing
- 🟡 Majority Element II - Arrays & Hashing
Topic: Trees
Problems:
- 🟡 Construct Binary Tree From Preorder And Inorder Traversal - Trees
- 🟡 House Robber III - Trees
Topic: Graphs
Problems:
- 🟡 Course Schedule II - Graphs
- 🟡 Graph Valid Tree - Graphs
Topic: Math & Geometry
Problems:
- 🟡 Multiply Strings - Math & Geometry
- 🟡 Detect Squares - Math & Geometry
Topic: 1-D Dynamic Programming
Problems:
- 🟡 Word Break - 1-D Dynamic Programming
- 🟡 Longest Increasing Subsequence - 1-D Dynamic Programming
Topic: Trees
Problems:
- 🟡 Delete Leaves With a Given Value - Trees
- 🔴 Binary Tree Maximum Path Sum - Trees
Topic: 1-D Dynamic Programming
Problems:
- 🟡 Partition Equal Subset Sum - 1-D Dynamic Programming
- 🟡 Combination Sum IV - 1-D Dynamic Programming
Topic: 1-D Dynamic Programming
Problems:
- 🟡 Perfect Squares - 1-D Dynamic Programming
- 🟡 Integer Break - 1-D Dynamic Programming
Topic: Greedy
Problems:
- 🟡 Merge Triplets to Form Target Triplet - Greedy
- 🟡 Partition Labels - Greedy
Topic: Backtracking
Problems:
- 🟡 Letter Combinations of a Phone Number - Backtracking
- 🟡 Matchsticks to Square - Backtracking
Topic: Graphs
Problems:
- 🟡 Course Schedule IV - Graphs
- 🟡 Number of Connected Components In An Undirected Graph - Graphs
Topic: Greedy
Problems:
- 🟡 Valid Parenthesis String - Greedy
- 🔴 Candy - Greedy
Topic: Trees
Problems:
- 🔴 Serialize And Deserialize Binary Tree - Trees
- 🟢 Invert Binary Tree - Trees
Topic: 2-D Dynamic Programming
Problems:
- 🟡 Last Stone Weight II - 2-D Dynamic Programming
- 🟡 Best Time to Buy And Sell Stock With Cooldown - 2-D Dynamic Programming
Topic: Graphs
Problems:
- 🟡 Redundant Connection - Graphs
- 🟡 Accounts Merge - Graphs
Topic: 2-D Dynamic Programming
Problems:
- 🟡 Coin Change II - 2-D Dynamic Programming
- 🟡 Target Sum - 2-D Dynamic Programming
Topic: Sliding Window
Problems:
- 🟡 Find K Closest Elements - Sliding Window
- 🔴 Minimum Window Substring - Sliding Window
Topic: Backtracking
Problems:
- 🟡 Partition to K Equal Sum Subsets - Backtracking
- 🔴 N Queens - Backtracking
Topic: 2-D Dynamic Programming
Problems:
- 🟡 Interleaving String - 2-D Dynamic Programming
- 🟡 Stone Game - 2-D Dynamic Programming
Topic: Binary Search
Problems:
- 🟡 Time Based Key Value Store - Binary Search
- 🔴 Split Array Largest Sum - Binary Search
Topic: 2-D Dynamic Programming
Problems:
- 🟡 Stone Game II - 2-D Dynamic Programming
- 🟡 Edit Distance - 2-D Dynamic Programming
Topic: Graphs
Problems:
- 🟡 Evaluate Division - Graphs
- 🟡 Minimum Height Trees - Graphs
Topic: Trees
Problems:
- 🟢 Maximum Depth of Binary Tree - Trees
- 🟢 Diameter of Binary Tree - Trees
Topic: 2-D Dynamic Programming
Problems:
- 🔴 Longest Increasing Path In a Matrix - 2-D Dynamic Programming
- 🔴 Distinct Subsequences - 2-D Dynamic Programming
Topic: Backtracking
Problems:
- 🔴 N Queens II - Backtracking
- 🔴 Word Break II - Backtracking
Topic: 2-D Dynamic Programming
Problems:
- 🔴 Burst Balloons - 2-D Dynamic Programming
- 🔴 Regular Expression Matching - 2-D Dynamic Programming
Topic: Binary Search
Problems:
- 🔴 Median of Two Sorted Arrays - Binary Search
- 🔴 Find in Mountain Array - Binary Search
Topic: Arrays & Hashing
Problems:
- 🟡 Subarray Sum Equals K - Arrays & Hashing
- 🔴 First Missing Positive - Arrays & Hashing
Topic: Trees
Problems:
- 🟢 Balanced Binary Tree - Trees
- 🟢 Same Tree - Trees
Topic: 1-D Dynamic Programming
Problems:
- 🔴 Stone Game III - 1-D Dynamic Programming
Topic: Intervals
Problems:
- 🔴 Minimum Interval to Include Each Query - Intervals
Topic: Math & Geometry
Problems:
- 🟢 Roman to Integer - Math & Geometry
Topic: Sliding Window
Problems:
- 🔴 Sliding Window Maximum - Sliding Window
Topic: Graphs
Problems:
- 🔴 Word Ladder - Graphs
Topic: Two Pointers
Problems:
- 🔴 Trapping Rain Water - Two Pointers
Topic: Stack
Problems:
- 🔴 Largest Rectangle In Histogram - Stack
Topic: Trees
Problems:
- 🟢 Subtree of Another Tree - Trees