Array

Problem Practice Difficulty YouTube Approach and Code
Roman To Integer leetcode Easy
Valid Parantheses leetcode Easy
Remove Duplicate from sorted array leetcode Easy
Remove Element leetcode Easy
Best Time to Buy and Sell Stock leetcode Easy
Best Time to Buy and Sell Stock II leetcode Easy
Intersection of Two Arrays II leetcode Easy
Single Number leetcode Easy
Contains Duplicate leetcode Easy

String

Problem Practice Difficulty YouTube Approach and Code
Reverse Words in a String LeetCode Easy
Longest Palindrome in a string LeetCode Easy
Check for Anagrams LeetCode Easy
Roman Number to Integer and vice versa LeetCode Medium
Implement ATOI/STRSTR LeetCode Medium
Longest Common Prefix LeetCode Medium
Z-Function LeetCode Medium
KMP algo / LPS(pi) array LeetCode Medium
Count and say LeetCode Medium

2 Pointer

Problem Practice Difficulty YouTube Approach and Code
Intersection of Two Arrays Easy
Maximum Ascending Subarray Sum Easy
Backspace String Compare Easy
Long Pressed Name Easy
Fruit Into Baskets Medium
Max Consecutive Ones III Medium
Container With Most Water Medium

Stack

Problem Practice Difficulty YouTube Approach and Code
Valid Parentheses Easy
Implement Queue using Stacks Easy
Min Stack Easy
Design Circular Queue Medium
Decode String Medium
Open the Lock Medium
Daily Temperatures Medium
Minimum Add to Make Parentheses Valid Medium

Queue

Problem Practice Difficulty YouTube Approach and Code
Valid Parentheses Easy
Implement Queue using Stacks Easy
Min Stack Easy
Design Circular Queue Medium
Decode String Medium
Open the Lock Medium
Daily Temperatures Medium
Minimum Add to Make Parentheses Valid Medium

Linked List

Problem Practice Difficulty YouTube Approach and Code
Delete Node in a Linked List Easy
Remove Nth Node From End of List Easy
Merge Two Sorted Lists Easy
Palindrome Linked List Easy
Linked List Cycle Easy
Intersection of Two Linked Lists Medium
Remove Linked List Elements Medium
Middle of the Linked List Medium
Merge k Sorted Lists Medium

Binary Search Tree

Problem Practice Difficulty YouTube Approach and Code
Binary Search Easy
Intersection of Two Arrays Easy
First Bad Version Easy
Arranging Coins Easy
Search Insert Position Easy
Search in Rotated Sorted Array Medium
Find First and Last Position of Element in Sorted Array Medium
Kth Smallest Element in a BST Medium
Find Peak Element Medium
Split Array Largest Sum Medium

Sliding Window

Problem Practice Difficulty YouTube Approach and Code
Longest Substring Without Repeating Characters Easy
Find All Anagrams in a String Easy
Minimum Window Substring Easy
Count Number of Nice Subarrays Easy
Fruit Into Baskets Easy

Recursion

Problem Practice Difficulty YouTube Approach and Code
Fibonacci Number Easy
Reverse String Easy
Reverse Linked List Easy
Search in a Binary Search Tree Easy
Climbing Stairs Easy
Pow(x, n) Medium
Swap Nodes in Pairs Hard

Backtracking

Problem Practice Difficulty YouTube Approach and Code
Word Search Easy
Subsets Easy
Subsets II Easy
Letter Case Permutation Easy
Combination Sum Medium
Letter Combinations of a Phone Number Medium
Combinations Medium
Combination Sum II Medium
Combination Sum III Medium
Combination Sum IV Medium
Permutations Medium
Permutations II Medium
Next Permutation Medium
N-Queens Hard

Tree

Problem Practice Difficulty YouTube Approach and Code
Binary Tree Preorder Traversal Easy
Binary Tree Inorder Traversal Easy
Binary Tree Postorder Traversal Easy
Validate Binary Search Tree Easy
Minimum Distance Between BST Nodes Easy
Symmetric Tree Easy
Same Tree Easy
Path Sum Easy
Maximum Depth of Binary Tree Easy
Convert Sorted Array to Binary Search Tree Easy
Validate Binary Search Tree Medium
Binary Search Tree Iterator Medium
Unique Binary Search Trees Medium
Serialize and Deserialize BST Medium
Binary Tree Right Side View Medium
Binary Tree Level Order Traversal Medium
Binary Tree Level Order Traversal II Medium
Binary Tree Zigzag Level Order Traversal Medium

Graph

Problem Practice Difficulty YouTube Approach and Code
Employee Importance Easy
Find the Town Judge Easy
Course Schedule II Medium
Redundant Connection Medium
Surrounded Regions Medium
Accounts Merge Medium
Network Delay Time Medium
Is Graph Bipartite? Medium
Find Eventual Safe States Medium
Keys and Rooms Medium
Possible Bipartition Medium
Most Stones Removed with Same Row or Column Medium
Rotting Oranges Medium
Number of Operations to Make Network Connected Medium

BFS And DFS

Problem Practice Difficulty YouTube Approach and Code
Flood Fill Easy
Binary Tree Preorder Traversal Easy
Number of Islands Medium
Walls and Gates Medium
Max Area of Island Medium
Number of Provinces Medium
Perfect Squares Medium
Course Schedule Medium
Detect Cycle in Undirected Graph Medium
Word Ladder Hard
01 Matrix Medium
Rotting Oranges Medium
All Paths from Source to Target Medium
Number of Closed Islands Medium

Dynamic Programming

Problem Practice Difficulty YouTube Approach and Code
Maximum Subarray Easy
Fibonacci Number Easy
Climbing Stairs Easy
Min Cost Climbing Stairs Easy
N-th Tribonacci Number Easy
Coin Change Medium
Minimum Falling Path Sum Medium
Minimum Cost For Tickets Medium
2 Keys Keyboard Medium
Maximum Product Subarray Medium
Triangle Medium
Ones and Zeroes Medium
Longest Arithmetic Subsequence Medium
Partition Equal Subset Sum Medium
House Robber Medium
Decode Ways Medium
Word Break Medium
Edit Distance Medium
Longest Increasing Subsequence Medium