A_To_Z DSA Course/Sheet

Introduction:

Welcome to my carefully curated list of Data Structures and Algorithms (DSA) problems. Here, you'll find detailed solutions for each problem, ranging from basic brute-force methods to highly optimized approaches. Whether you're gearing up for coding interviews or aiming to enhance your algorithmic problem-solving abilities, this page serves as your go-to resource.

How to Use This Page:

All problems are organized into specific categories such as Dynamic Programming, Graph Algorithms, and others, allowing you to easily navigate and find what you're looking for. For each problem, multiple solution levels are provided, including:

• Brute Force Solution: A basic approach that solves the problem but might not be the most efficient.
• Better Solution: An enhanced method that lowers time complexity, resulting in a faster solution.
• Optimal Solution: The most optimal approach in terms of time complexity.
• Space Optimization: An optimized version of the solution that also reduces space complexity.

Why Focus on Different Solutions?

In practical situations, the most efficient solution may not always be required or might be overly complex for the task at hand. By exploring and applying various approaches, you'll be better prepared to select the most suitable solution based on the specific constraints and needs of the problem.

Get Started

Browse the problems by category, experiment with the solutions, and enhance your problem-solving abilities. Don’t hesitate to share comments or suggestions if you have different methods or improvements to propose.

Problem Categories:

Sr. No	Problem	Article	Practice	Difficulty
1	Merge Sorted Array	📄	📝	Easy
2	Remove Element	📄	📝	Easy
3	Remove Duplicates from Sorted Array	📄	📝	Easy
4	Remove Duplicates from Sorted Array II	📄	📝	Medium
5	Majority Element	📄	📝	Easy
6	Rotate Array	📄	📝	Medium
7	Best Time to Buy and Sell Stock	📄	📝	Easy
8	Best Time to Buy and Sell Stock II	📄	📝	Medium
9	Jump Game	📄	📝	Medium
10	Jump Game II	📄	📝	Medium
11	H-Index	📄	📝	Medium
12	Insert Delete GetRandom O(1)	📄	📝	Medium
13	Product of Array Except Self	📄	📝	Medium
14	Gas Station	📄	📝	Medium
15	Candy	📄	📝	Hard
16	Trapping Rain Water	📄	📝	Hard
17	Roman to Integer	📄	📝	Easy
18	Integer to Roman	📄	📝	Medium
19	Length of Last Word	📄	📝	Easy
20	Longest Common Prefix	📄	📝	Easy
21	Reverse Words in a String	📄	📝	Medium
22	Zigzag Conversion	📄	📝	Medium
23	Find the Index of the First Occurrence in a String	📄	📝	Easy
24	Text Justification	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Valid Palindrome	📄	📝	Easy
2	Is Subsequence	📄	📝	Easy
3	Two Sum II - Input Array Is Sorted	📄	📝	Medium
4	Container With Most Water	📄	📝	Medium
5	3Sum	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Minimum Size Subarray Sum	📄	📝	Medium
2	Longest Substring Without Repeating Characters	📄	📝	Medium
3	Substring with Concatenation of All Words	📄	📝	Hard
4	Minimum Window Substring	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Valid Sudoku	📄	📝	Medium
2	Spiral Matrix	📄	📝	Medium
3	Rotate Image	📄	📝	Medium
4	Set Matrix Zeroes	📄	📝	Medium
5	Game of Life	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Ransom Note	📄	📝	Easy
2	Isomorphic Strings	📄	📝	Easy
3	Word Pattern	📄	📝	Easy
4	Valid Anagram	📄	📝	Easy
5	Group Anagrams	📄	📝	Medium
6	Two Sum	📄	📝	Easy
7	Happy Number	📄	📝	Easy
8	Contains Duplicate II	📄	📝	Easy
9	Longest Consecutive Sequence	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Summary Ranges	📄	📝	Easy
2	Merge Intervals	📄	📝	Medium
3	Insert Interval	📄	📝	Medium
4	Minimum Number of Arrows to Burst Balloons	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Valid Parentheses	📄	📝	Easy
2	Simplify Path	📄	📝	Medium
3	Min Stack	📄	📝	Medium
4	Evaluate Reverse Polish Notation	📄	📝	Medium
5	Basic Calculator	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Linked List Cycle	📄	📝	Easy
2	Add Two Numbers	📄	📝	Medium
3	Merge Two Sorted Lists	📄	📝	Easy
4	Copy List with Random Pointer	📄	📝	Medium
5	Reverse Linked List II	📄	📝	Medium
6	Reverse Nodes in k-Group	📄	📝	Hard
7	Remove Nth Node From End of List	📄	📝	Medium
8	Remove Duplicates from Sorted List II	📄	📝	Medium
9	Rotate List	📄	📝	Medium
10	Partition List	📄	📝	Medium
11	LRU Cache	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Maximum Depth of Binary Tree	📄	📝	Easy
2	Same Tree	📄	📝	Easy
3	Invert Binary Tree	📄	📝	Easy
4	Symmetric Tree	📄	📝	Easy
5	Construct Binary Tree from Preorder and Inorder Traversal	📄	📝	Medium
6	Construct Binary Tree from Inorder and Postorder Traversal	📄	📝	Medium
7	Populating Next Right Pointers in Each Node II	📄	📝	Medium
8	Flatten Binary Tree to Linked List	📄	📝	Medium
9	Path Sum	📄	📝	Easy
10	Sum Root to Leaf Numbers	📄	📝	Medium
11	Binary Tree Maximum Path Sum	📄	📝	Hard
12	Binary Search Tree Iterator	📄	📝	Medium
13	Count Complete Tree Nodes	📄	📝	Easy
14	Lowest Common Ancestor of a Binary Tree	📄	📝	Medium
15	Binary Tree Right Side View	📄	📝	Medium
16	Average of Levels in Binary Tree	📄	📝	Easy
17	Binary Tree Level Order Traversal	📄	📝	Medium
18	Binary Tree Zigzag Level Order Traversal	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Binary Tree Right Side View	📄	📝	Medium
2	Average of Levels in Binary Tree	📄	📝	Easy
3	Binary Tree Level Order Traversal	📄	📝	Medium
4	Binary Tree Zigzag Level Order Traversal	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Minimum Absolute Difference in BST	📄	📝	Easy
2	Kth Smallest Element in a BST	📄	📝	Medium
3	Validate Binary Search Tree	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Number of Islands	📄	📝	Medium
2	Surrounded Regions	📄	📝	Medium
3	Clone Graph	📄	📝	Medium
4	Evaluate Division	📄	📝	Medium
5	Course Schedule	📄	📝	Medium
6	Course Schedule II	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Snakes and Ladders	📄	📝	Medium
2	Minimum Genetic Mutation	📄	📝	Medium
3	Word Ladder	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Implement Trie (Prefix Tree)	📄	📝	Medium
2	Design Add and Search Words Data Structure	📄	📝	Medium
3	Word Search II	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Letter Combinations of a Phone Number	📄	📝	Medium
2	Combinations	📄	📝	Medium
3	Permutations	📄	📝	Medium
4	Combination Sum	📄	📝	Medium
5	N-Queens II	📄	📝	Hard
6	Generate Parentheses	📄	📝	Medium
7	Word Search	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Convert Sorted Array to Binary Search Tree	📄	📝	Easy
2	Sort List	📄	📝	Medium
3	Construct Quad Tree	📄	📝	Medium
4	Merge k Sorted Lists	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Maximum Subarray	📄	📝	Medium
2	Maximum Sum Circular Subarray	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Search Insert Position	📄	📝	Easy
2	Search a 2D Matrix	📄	📝	Medium
3	Find Peak Element	📄	📝	Medium
4	Search in Rotated Sorted Array	📄	📝	Medium
5	Find First and Last Position of Element in Sorted Array	📄	📝	Medium
6	Find Minimum in Rotated Sorted Array	📄	📝	Medium
7	Median of Two Sorted Arrays	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Kth Largest Element in an Array	📄	📝	Medium
2	IPO	📄	📝	Hard
3	Find K Pairs with Smallest Sums	📄	📝	Medium
4	Find Median from Data Stream	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Add Binary	📄	📝	Easy
2	Reverse Bits	📄	📝	Easy
3	Number of 1 Bits	📄	📝	Easy
4	Single Number	📄	📝	Easy
5	Single Number II	📄	📝	Medium
6	Bitwise AND of Numbers Range	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Palindrome Number	📄	📝	Easy
2	Plus One	📄	📝	Easy
3	Factorial Trailing Zeroes	📄	📝	Medium
4	Sqrt(x)	📄	📝	Easy
5	Pow(x, n)	📄	📝	Medium
6	Max Points on a Line	📄	📝	Hard

Sr. No	Problem	Article	Practice	Difficulty
1	Climbing Stairs	📄	📝	Easy
2	House Robber	📄	📝	Medium
3	Word Break	📄	📝	Medium
4	Coin Change	📄	📝	Medium
5	Longest Increasing Subsequence	📄	📝	Medium

Sr. No	Problem	Article	Practice	Difficulty
1	Triangle	📄	📝	Medium
2	Minimum Path Sum	📄	📝	Medium
3	Unique Paths II	📄	📝	Medium
4	Longest Palindromic Substring	📄	📝	Medium
5	Interleaving String	📄	📝	Medium
6	Edit Distance	📄	📝	Medium

Summary

This approach offers a well-organized method for presenting your solutions, leading readers through the problem-solving process in a step-by-step manner. You can tailor the tone and specifics to match your personal style or target audience.