Friday, August 1, 2025

INTRO OF DS AND ALGO

🧱 DATA STRUCTURES – "How data is organized"

Core Goal: Efficiently store, access, and manipulate data.

 



Category Concepts You Must Master Real-Life Analogy

Array Indexing, Iteration, Static size Shelf with fixed compartments

Linked List Nodes, Pointers, Dynamic size Train cars linked together

Stack LIFO, Push/Pop Plates stacked in a cafeteria

Queue FIFO, Enqueue/Dequeue Waiting line at a ticket counter

Hash Map / Hash Table Key-value pairs, Hash functions Dictionary

Tree Hierarchy, Traversals (DFS, BFS) Family tree

Binary Search Tree (BST) Ordered nodes, Search in O(log n) Sorted filing system

Heap (Min/Max) Priority Queue, Top-K Task manager prioritizing
 processes

Trie Prefix tree, String search Phonebook with prefix-based lookup

Graph Nodes + Edges, Directed/Undirected Road map or social network





⚙️ ALGORITHMS – "How problems are solved using data"

Core Goal: Apply logic to manipulate data structures efficiently.

Technique Concepts You Must Master Example Problem Types

Recursion Base case, Call stack Factorial, Tower of Hanoi

Backtracking Try all possibilities, undo steps Sudoku, N-Queens

Greedy Best choice at each step Activity selection, Huffman coding

Divide & Conquer Break into subproblems Merge sort, Quick sort

Binary Search Sorted input, Halve search space Find element, Rotated array

Dynamic Programming Optimal substructure, Memoization Knapsack, Fibonacci, LIS

Graph Algorithms DFS, BFS, Dijkstra, Union-Find Shortest path, Cycle detection

Sorting Bubble, Merge, Quick, Heap sort Arrange items efficiently

Sliding Window Fixed/variable range over array Max sum subarray, Anagram check

Two Pointers Start/end movement Sorted array problems, Palindrome check

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