Easy

Array&HASH

  • Contains Duplicate
  • Valid Anagram
  • Two Sum

Stack

  • Valid Parentheses

Two Pointers

  • Valid Palindrome
  • Binary Search

Sliding Window

  • Best Time to Buy And Sell Stock

Linked List

  • Reverse Linked List
  • Merge Two Sorted Lists
  • Linked List Cycle

Trees

  • Invert Binary Tree
  • Maximum Depth of Binary Tree
  • Diameter of Binary Tree
  • Balanced Binary Tree
  • Same Tree
  • Subtree of Another Tree

Tries

Backtracking

Heap / Priority Queue

  • Kth Largest Element In a Stream
  • Last Stone Weight

Intervals

  • Meeting Rooms

Greedy

Graphs

1-D Dynamic Programming

  • Climbing Stairs
  • Min Cost Climbing Stairs

Advanced Graphs

2-D Dynamic Programming

Bit Manipulation

  • Single Number
  • Number of 1 Bits
  • Counting Bits
  • Reverse Bits
  • Missing Number

Math & Geometry

  • Happy Number
  • Plus One