Schedule | 6 weeks | 16 hours per week

Questions grouped by difficulty | Easy: 31, Medium: 68, Hard: 12

Array: 16, Binary: 4, Binary Search: 6, Binary Search Tree: 3, Binary Tree: 13, Dynamic Programming: 8, Graph: 14, Hash Table: 1, Heap: 6, Linked List: 8, Math: 1, Matrix: 2, Recursion: 4, Stack: 11, String: 11, Trie: 3

Completed 49 / 111

Week 1

• 1 - Two Sum | Easy | 15 mins | Array
• 2 - Valid Parentheses | Easy | 20 mins | Stack
• 3 - Merge Two Sorted Lists | Easy | 20 mins | Linked List
• 4 - Best Time to Buy and Sell Stock | Easy | 20 mins | Array
• 5 - Valid Palindrome | Easy | 15 mins | String
• 6 - Invert Binary Tree | Easy | 15 mins | Binary Tree
• 7 - Valid Anagram | Easy | 15 mins | String
• 8 - Binary Search | Easy | 15 mins | Binary Search
• 9 - Flood Fill | Easy | 20 mins | Graph
• 10 - Lowest Common Ancestor of a Binary Search Tree | Easy | 20 mins | Binary Search Tree
• 11 - Balanced Binary Tree | Easy | 15 mins | Binary Tree
• 12 - Linked List Cycle | Easy | 20 mins | Linked List
• 13 - Implement Queue using Stacks | Easy | 20 mins | Stack
• 14 - First Bad Version | Easy | 20 mins | Binary Search
• 15 - Ransom Note | Easy | 15 mins | Hash Table
• 16 - Climbing Stairs | Easy | 20 mins | Dynamic Programming
• 17 - Longest Palindrome | Easy | 20 mins | String
• 18 - Reverse Linked List | Easy | 20 mins | Linked List
• 19 - Majority Element | Easy | 20 mins | Array
• 20 - Add Binary | Easy | 15 mins | Binary
• 21 - Diameter of Binary Tree | Easy | 30 mins | Binary Tree
• 22 - Middle of the Linked List | Easy | 20 mins | Linked List
• 23 - Maximum Depth of Binary Tree | Easy | 15 mins | Binary Tree
• 24 - Contains Duplicate | Easy | 15 mins | Array
• 25 - Meeting Rooms | Easy | 20 mins | Array
• 26 - Roman to Integer | Easy | 20 mins | Math

Week 2

• 1 - Backspace String Compare | Easy | 15 mins | Stack
• 2 - Counting Bits | Easy | 15 mins | Binary
• 3 - Same Tree | Easy | 20 mins | Binary Tree
• 4 - Number of 1 Bits | Easy | 15 mins | Binary
• 5 - Longest Common Prefix | Easy | 20 mins | String
• 6 - Maximum Subarray | Medium | 20 mins | Dynamic Programming
• 7 - Insert Interval | Medium | 25 mins | Array
• 8 - 01 Matrix | Medium | 30 mins | Graph
• 9 - K Closest Points to Origin | Medium | 30 mins | Heap
• 10 - Longest Substring Without Repeating Characters | Medium | 30 mins | String
• 11 - 3Sum | Medium | 30 mins | Array
• 12 - Binary Tree Level Order Traversal | Medium | 20 mins | Binary Tree
• 13 - Clone Graph | Medium | 25 mins | Graph
• 14 - Evaluate Reverse Polish Notation | Medium | 30 mins | Stack
• 15 - Course Schedule | Medium | 30 mins | Graph
• 16 - Implement Trie (Prefix Tree) | Medium | 35 mins | Trie
• 17 - Coin Change | Medium | 25 mins | Dynamic Programming
• 18 - Product of Array Except Self | Medium | 30 mins | Array
• 19 - Min Stack | Medium | 20 mins | Stack
• 20 - Validate Binary Search Tree | Medium | 20 mins | Binary Search Tree

Week 3

• 1 - Number of Islands | Medium | 25 mins | Graph
• 2 - Rotting Oranges | Medium | 30 mins | Graph
• 3 - Search in Rotated Sorted Array | Medium | 30 mins | Binary Search
• 4 - Combination Sum | Medium | 30 mins | Array
• 5 - Permutations | Medium | 30 mins | Recursion
• 6 - Merge Intervals | Medium | 30 mins | Array
• 7 - Lowest Common Ancestor of a Binary Tree | Medium | 25 mins | Binary Tree
• 8 - Time Based Key-Value Store | Medium | 35 mins | Binary Search
• 9 - Accounts Merge | Medium | 30 mins | Graph
• 10 - Sort Colors | Medium | 25 mins | Array
• 11 - Word Break | Medium | 30 mins | Trie
• 12 - Partition Equal Subset Sum | Medium | 30 mins | Dynamic Programming
• 13 - String to Integer (atoi) | Medium | 25 mins | String
• 14 - Spiral Matrix | Medium | 25 mins | Matrix
• 15 - Subsets | Medium | 30 mins | Recursion
• 16 - Binary Tree Right Side View | Medium | 20 mins | Binary Tree
• 17 - Longest Palindromic Substring | Medium | 25 mins | String

Week 4

• 1 - Unique Paths | Medium | 20 mins | Dynamic Programming
• 2 - Construct Binary Tree from Preorder and Inorder Traversal | Medium | 25 mins | Binary Tree
• 3 - Container With Most Water | Medium | 35 mins | Array
• 4 - Letter Combinations of a Phone Number | Medium | 30 mins | Recursion
• 5 - Word Search | Medium | 30 mins | Graph
• 6 - Find All Anagrams in a String | Medium | 30 mins | String
• 7 - Minimum Height Trees | Medium | 30 mins | Graph
• 8 - Task Scheduler | Medium | 35 mins | Heap
• 9 - LRU Cache | Medium | 30 mins | Linked List
• 10 - Kth Smallest Element in a BST | Medium | 25 mins | Binary Search Tree
• 11 - Daily Temperatures | Medium | 30 mins | Stack
• 12 - House Robber | Medium | 25 mins | Dynamic Programming
• 13 - Gas Station | Medium | 30 mins | Array
• 14 - Next Permutation | Medium | 30 mins | Recursion
• 15 - Valid Sudoku | Medium | 35 mins | Matrix
• 16 - Group Anagrams | Medium | 25 mins | String

Week 5

• 1 - Maximum Product Subarray | Medium | 30 mins | Dynamic Programming
• 2 - Design Add and Search Words Data Structure | Medium | 35 mins | Trie
• 3 - Pacific Atlantic Water Flow | Medium | 30 mins | Graph
• 4 - Remove Nth Node From End of List | Medium | 20 mins | Linked List
• 5 - Shortest Path to Get Food | Medium | 30 mins | Graph
• 6 - Find the Duplicate Number | Medium | 20 mins | Binary
• 7 - Top K Frequent Words | Medium | 30 mins | Heap
• 8 - Longest Increasing Subsequence | Medium | 30 mins | Dynamic Programming
• 9 - Graph Valid Tree | Medium | 30 mins | Graph
• 10 - Course Schedule II | Medium | 35 mins | Graph
• 11 - Swap Nodes in Pairs | Medium | 25 mins | Linked List
• 12 - Path Sum II | Medium | 25 mins | Binary Tree
• 13 - Longest Consecutive Sequence | Medium | 30 mins | Array
• 14 - Rotate Array | Medium | 25 mins | Array
• 15 - Odd Even Linked List | Medium | 25 mins | Linked List
• 16 - Decode String | Medium | 30 mins | Stack
• 17 - Contiguous Array | Medium | 30 mins | Array

Week 6

• 1 - Maximum Width of Binary Tree | Medium | 20 mins | Binary Tree
• 2 - Find K Closest Elements | Medium | 30 mins | Heap
• 3 - Longest Repeating Character Replacement | Medium | 30 mins | String
• 4 - Minimum Window Substring | Hard | 30 mins | String
• 5 - Serialize and Deserialize Binary Tree | Hard | 40 mins | Binary Tree
• 6 - Trapping Rain Water | Hard | 35 mins | Stack
• 7 - Find Median from Data Stream | Hard | 30 mins | Heap
• 8 - Word Ladder | Hard | 45 mins | Graph
• 9 - Basic Calculator | Hard | 40 mins | Stack
• 10 - Maximum Profit in Job Scheduling | Hard | 45 mins | Binary Search
• 11 - Merge k Sorted Lists | Hard | 30 mins | Heap
• 12 - Largest Rectangle in Histogram | Hard | 35 mins | Stack
• 13 - Binary Tree Maximum Path Sum | Hard | 35 mins | Binary Tree
• 14 - Maximum Frequency Stack | Hard | 40 mins | Stack
• 15 - Median of Two Sorted Arrays | Hard | 40 mins | Binary Search