dsa-algorithms-practices

DSA & Algorithm practices

🧠 Data Structures and Algorithms - 40 Must-Solve Problems (To-Do List)

This is a curated list of essential DSA problems to practice and master key concepts. Each problem is grouped by category, and comes with an example prompt.

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✅ Arrays and Strings

• 1. Find the maximum sum subarray
  Example: Kadane's Algorithm

• 2. Find all substrings that are palindromes
  Example: Palindrome Partitioning

• 3. Implement the "two sum" problem
  Example: Two Sum

• 4. Implement Kadane's algorithm for maximum subarray sum
  Example: Maximum Subarray

• 5. Find the missing number in an array of integers
  Example: Missing Number

• 6. Merge two sorted arrays into one sorted array
  Example: Merge Sorted Array

• 7. Check if a string is a palindrome
  Example: Valid Palindrome

• 8. Find the first non-repeating character in a string
  Example: First Unique Character

• 9. Remove duplicates from a sorted array
  Example: Remove Duplicates

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🔗 Linked Lists

• 10. Reverse a linked list
  Example: Reverse Linked List

• 11. Detect a cycle in a linked list
  Example: Linked List Cycle

• 12. Find the middle of a linked list
  Example: Middle of the Linked List

• 13. Merge two sorted linked lists
  Example: Merge Two Sorted Lists

• 14. Implement a stack using linked list
  Example: Custom implementation (no standard problem)

• 15. Find the intersection point of two linked lists
  Example: Intersection of Two Linked Lists

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🧱 Stacks and Queues

• 16. Implement a stack using an array
  Example: Custom implementation

• 17. Stack with min operation
  Example: Min Stack

• 18. Implement a circular queue
  Example: Design Circular Queue

• 19. Design a max stack
  Example: Max Stack (Hard)

• 20. Design a queue using stacks
  Example: Implement Queue using Stacks

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🌳 Trees and Binary Search Trees

• 21. Find the height of a binary tree
  Example: Maximum Depth of Binary Tree

• 22. Find LCA of two nodes
  Example: Lowest Common Ancestor

• 23. Validate if a binary tree is BST
  Example: Validate BST

• 24. Serialize and deserialize a binary tree
  Example: Serialize and Deserialize Binary Tree

• 25. Inorder traversal
  Example: Binary Tree Inorder Traversal

• 26. Find the diameter of a binary tree
  Example: Diameter of Binary Tree

• 27. Convert to mirror tree
  Example: Mirror Tree

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🔁 Graphs

• 28. Implement DFS
  Example: Graph DFS Traversal

• 29. Implement BFS
  Example: Graph BFS Traversal

• 30. Find shortest path (unweighted)
  Example: 01 Matrix

• 31. Detect a cycle (undirected graph, DFS)
  Example: Cycle Detection

• 32. Check if graph is bipartite
  Example: Is Graph Bipartite?

• 33. Count connected components
  Example: Number of Provinces

• 34. Find bridges in a graph
  Example: Critical Connections

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🔍 Sorting and Searching

• 35. Implement bubble, insertion, selection, merge sort
  Example: Manual implementation

• 36. Implement quicksort
  Example: Quicksort

• 37. Implement binary search
  Example: Binary Search

• 38. Implement interpolation search
  Example: Interpolation Search

• 39. Kth smallest element
  Example: Kth Smallest in Array

• 40. Count inversions
  Example: Count Inversions

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🚀 Coming Next Week!

🧮 Dynamic Programming
🔁 Backtracking
🔢 Hashing
📚 Heaps
🌲 Tries
🎯 Greedy Algorithms

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💡 Tip: Track your progress by checking off problems as you solve them!