All problems

Every problem has an animated, line-by-line trace in Java, Python and C++, with complexity, the key idea, common mistakes and edge cases.

Arrays & Hashing

• Two Sum easy
• Valid Anagram easy
• Contains Duplicate easy
• Majority Element easy
• Group Anagrams medium
• Top K Frequent Elements medium
• Product of Array Except Self medium
• Longest Consecutive Sequence medium

Two Pointers

• Valid Palindrome easy
• Move Zeroes easy
• Two Sum II - Input Array Is Sorted medium
• Sort Colors medium
• 3Sum medium
• Container With Most Water medium
• Trapping Rain Water hard

Sliding Window

• Best Time to Buy and Sell Stock easy
• Longest Substring Without Repeating Characters medium
• Max Consecutive Ones III medium
• Fruit Into Baskets medium
• Longest Repeating Character Replacement medium
• Permutation in String medium
• Minimum Window Substring hard

Binary Search

• Binary Search easy
• Search Insert Position easy
• Find Minimum in Rotated Sorted Array medium
• Search a 2D Matrix medium
• Search in Rotated Sorted Array medium
• Koko Eating Bananas medium
• Capacity To Ship Packages Within D Days medium

Stack

• Valid Parentheses easy
• Min Stack medium
• Next Greater Element I easy
• Evaluate Reverse Polish Notation medium
• Daily Temperatures medium
• Asteroid Collision medium
• Largest Rectangle in Histogram hard

Linked List

• Reverse Linked List easy
• Merge Two Sorted Lists easy
• Linked List Cycle easy
• Middle of the Linked List easy
• Remove Nth Node From End of List medium
• Reorder List medium
• LRU Cache medium
• Merge k Sorted Lists hard

Trees: Traversal

• Maximum Depth of Binary Tree easy
• Invert Binary Tree easy
• Same Tree easy
• Balanced Binary Tree easy
• Diameter of Binary Tree easy
• Binary Tree Level Order Traversal medium
• Binary Tree Right Side View medium
• Binary Tree Zigzag Level Order Traversal medium

Trees: BST & Advanced

• Validate Binary Search Tree medium
• Kth Smallest Element in a BST medium
• Lowest Common Ancestor of a Binary Search Tree medium
• Lowest Common Ancestor of a Binary Tree medium
• Construct Binary Tree from Preorder and Inorder Traversal medium
• Binary Tree Maximum Path Sum hard
• Serialize and Deserialize Binary Tree hard

Heap / Priority Queue

• Kth Largest Element in an Array medium
• Last Stone Weight easy
• K Closest Points to Origin medium
• Task Scheduler medium
• Top K Frequent Words medium
• Reorganize String medium
• Find Median from Data Stream hard

Graphs: BFS / DFS

• Flood Fill easy
• Number of Islands medium
• Max Area of Island medium
• Clone Graph medium
• Rotting Oranges medium
• 01 Matrix medium
• Surrounded Regions medium
• Pacific Atlantic Water Flow medium

Graphs: Topological Sort & Union-Find

• Course Schedule medium
• Number of Provinces medium
• Find Eventual Safe States medium
• Course Schedule II medium
• Redundant Connection medium
• Accounts Merge medium
• Word Ladder hard

Backtracking

• Subsets medium
• Permutations medium
• Combination Sum medium
• Subsets II medium
• Combination Sum II medium
• Word Search medium
• Palindrome Partitioning medium
• N-Queens hard

1D Dynamic Programming

• Climbing Stairs easy
• Min Cost Climbing Stairs easy
• House Robber medium
• House Robber II medium
• Coin Change medium
• Longest Increasing Subsequence medium
• Word Break medium
• Decode Ways medium

2D Dynamic Programming

• Unique Paths medium
• Minimum Path Sum medium
• Longest Common Subsequence medium
• Partition Equal Subset Sum medium
• Coin Change II medium
• Target Sum medium
• Edit Distance medium
• Best Time to Buy and Sell Stock with Cooldown medium

Greedy & Intervals

• Maximum Subarray medium
• Jump Game medium
• Merge Intervals medium
• Insert Interval medium
• Jump Game II medium
• Gas Station medium
• Non-overlapping Intervals medium
• Minimum Number of Arrows to Burst Balloons medium

Trie & Strings

• Implement Trie (Prefix Tree) medium
• Longest Common Prefix easy
• Palindromic Substrings medium
• Design Add and Search Words Data Structure medium
• Search Suggestions System medium
• Longest Palindromic Substring medium
• Word Search II hard

Advanced Graphs (Dijkstra / MST)

• Network Delay Time medium
• Shortest Path in Binary Matrix medium
• Min Cost to Connect All Points medium
• Cheapest Flights Within K Stops medium
• Path With Minimum Effort medium
• Swim in Rising Water hard

OA Simulation: 2 problems in 90 min each round

• Maximum Units on a Truck easy
• Count Number of Teams medium
• Number of Ways to Select Buildings medium
• Sum of Total Strength of Wizards hard

Amazon-tagged: Arrays & Strings

• Subarray Sum Equals K medium
• Find All Anagrams in a String medium
• String Compression medium
• Next Permutation medium
• Spiral Matrix medium
• Rotate Image medium
• Set Matrix Zeroes medium

Amazon-tagged: Mixed

• Copy List with Random Pointer medium
• Decode String medium
• Find the Duplicate Number medium
• Valid Sudoku medium
• Basic Calculator II medium
• Sliding Window Maximum hard
• First Missing Positive hard

Amazon-tagged: Design-style coding

• Insert Delete GetRandom O(1) medium
• Time Based Key-Value Store medium
• Design Underground System medium
• Snapshot Array medium
• Design Twitter medium
• Maximum Frequency Stack hard

Amazon-tagged: Trees & Matrix (mock day)

• All Nodes Distance K in Binary Tree medium
• Path Sum II medium
• Flatten Binary Tree to Linked List medium
• Maximal Square medium
• Vertical Order Traversal of a Binary Tree hard
• Longest Increasing Path in a Matrix hard

Weak areas: redo your mistakes notebook + new

• Game of Life medium
• 3Sum Closest medium
• Integer to English Words hard