LinkedList

• Linked List Cycle
• Linked List Cycle II
• Remove Duplicates from Sorted List
• Remove Duplicates from Sorted List II
• Add Two Numbers

Stack

• Valid Parentheses
• Reverse Linked List

Heap, PriorityQueue

• Kth Largest Element in a Stream
• Top K Frequent Elements
• Find K Pairs with Smallest Sums

HashMap

• Two Sum
• Group Anagrams
• Intersection of Two Arrays
• Unique Email Addresses
• First Unique Character in a String
• Subarray Sum Equals K

Graph, BFS, DFS

• Number of Islands
• Max Area of Island
• Word Ladder

Tree, BST

• Minimum Depth of Binary Tree
• Merge Two Binary Trees
• Convert Sorted Array to Binary Search Tree
• Path Sum
• Binary Tree Level Order Traversal
• Binary Tree Zigzag Level Order Traversal
• Validate Binary Search Tree
• Construct Binary Tree from Preorder and Inorder Traversal

Dynamic Programming

• Longest Increasing Subsequence
• Maximum Subarray
• Unique Paths
• Unique Paths II
• House Robber
• House Robber II
• Best Time to Buy and Sell Stock
• Best Time to Buy and Sell Stock II
• Word Break
• Coin Change

Binary Search

• Search Insert Position
• Find Minimum in Rotated Sorted Array
• Search in Rotated Sorted Array
• Capacity To Ship Packages Within D Days

Recursion

• Pow(x, n)
• K-th Symbol in Grammar

Sliding Window

• Longest Substring Without Repeating Characters
• Minimum Size Subarray Sum

Greedy + Backtracking

• Permutations
• Subsets
• Combination Sum
• Generate Parentheses

Other

• Move Zeroes
• Is Subsequence
• Next Permutation
• String to Integer (atoi)
• ZigZag Conversion