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DataStructures - 30 Days🚀

Author - Santhosh Pandi🦊

Acknowledgment:

The structure for this DSA learning roadmap was inspired by an Instagram reel. Unfortunately, I am unable to credit the original creator, as the source is unknown. All credit for the learning path goes to them.

The programs, designs, and implementations in this repository were created by me.

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Week 1: Basics of DSA⚡

Day 1-2: Basics of Programming🔥

Learn

• Time Complexity and Space Complexity
• Big-O Notation

Practice

• Analyze the time complexity of simple programs.

Resources

• "Introduction to Algorithms" by Cormen (Chapter 1 on complexity)
• Online videos on Big-O

Day 3-4: Arrays and Strings🔥

Topics Basics

• Sliding window

• Two-pointer techniques

Problems

• Find the maximum sum subarray (Kadane's Algorithm)
• Two Sum Problem
• Longest Substring Without Repeating Characters

Practice Sites

• LeetCode

• HackerRank

• GeeksforGeeks

Day 5: Sorting Algorithms🔥

Learn

• Bubble, Selection, Insertion, Merge, Quick Sort

Practice

• Implement sorting algorithms and understand time complexity.
• Focus on Merge Sort and Quick Sort.

Day 6-7: Linked Lists🔥

Topics

• Singly, Doubly, and Circular Linked Lists

Problems

• Reverse a Linked List

• Detect a Cycle in a Linked List (Floyd's Algorithm) Merge Two Sorted Linked Lists

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Week 2: Intermediate DSA⚡

Focus

Explore recursion, stacks, queues, and hashmaps.

Day 8-9: Recursion and Backtracking Learn🔥

• Basics of recursion, its stack behavior.

Problems

• Factorial, Fibonacci numbers
• Subset Sum Problem, N-Queens Problem

Day 10-11: Stacks and Queues🔥

Topics

• Implement stacks and queues using arrays and linked lists.

Problems

• Next Greater Element
• Valid Parentheses
• Implement a Queue using Two Stacks

Day 12-13: Hashmaps and Hashing🔥

Learn

• Use cases, collision handling.

Problems

• Two Sum (using hashmaps)
• Subarray Sum Equals K
• Longest Consecutive Sequence

Day 14: Practice Problems🔥

• Solve 5-10 problems covering arrays, strings, and hashmaps.

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Week 3: Advanced DSA⚡

Focus

Trees, graphs, and advanced algorithms.

Day 15-17: Trees🔥

Topics

• Binary Search Trees

• Avl Tree (Self Balancing BST)

Problems

• Inorder, Preorder, Postorder Traversals
• Lowest Common Ancestor (LCA)
• Validate a Binary Search Tree

Resources

• visualgo.net
• Geeks for Geeks

Day 18-19: Graphs🔥

Topics

• BFS
• DFS
• Adjacency list/matrix representations

Problems

• Detect a Cycle in a Graph

• Shortest Path in an Unweighted Graph (BFS)

• Connected Components in a Graph

Day 20-21: Greedy Algorithms Learn🔥

• Concept and real-world examples

Problems

• Activity Selection Problem

• Minimum Number of Platforms

• Huffman Encoding

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Week 4: Competitive DSA⚡

Focus

Dynamic Programming (DP) and revision.

Day 22-24: Dynamic Programming🔥

Topics

• Understand memoization and tabulation.

Problems

• Fibonacci (Top-Down and Bottom-Up).

• 0/1 Knapsack Problem.

• Longest Increasing Subsequence.

Day 25-27: Revision and Mock Contests Revise🔥

• Revise all major topics and solve problems from past contests.

Mock Contests

• Attempt 1-2 timed contests on LeetCode or Codeforces.

Day 28-30: Final Revision🔥

Revise

• Your notes, formulas, and common patterns.

Practice

• Problems that were challenging for you earlier.