CS201 Data Structures and Algorithms Complete Study Guide – Exam Ready Notes

Data Structures & Algorithms
Complete Study Guide with Complexity Analysis
CS201 – Data Structures and Algorithms
Undergraduate Computer Science
Comprehensive Study Guide | Exam Ready

, 1. Introduction to Data Structures
A data structure is a specialized format for organizing, processing, retrieving, and storing data.
Choosing the right data structure is critical for writing efficient algorithms.


1.1 Why Data Structures Matter
• Efficiency: Proper data structures reduce time and space complexity
• Organization: Help manage large amounts of data effectively
• Reusability: Standard structures can be reused across different problems
• Abstraction: Hide implementation details from the user


1.2 Classification of Data Structures
Category Type Examples Use Case
Linear Static Array Fixed-size sequential storage
Linear Dynamic Linked List, Stack, Variable-size sequential data
Queue
Non-Linear Hierarchical Tree, Heap Parent-child relationships
Non-Linear Graph-based Graph Networks, maps, relationships
Hash-based Key-Value Hash Table Fast lookups by key




2. Arrays
An array is a collection of elements stored at contiguous memory locations. It is the simplest
and most widely used data structure.

2.1 Array Operations & Complexity
Operation Best Case Average Case Worst Case
Access O(1) O(1) O(1)
Search (linear) O(1) O(n) O(n)
Search (binary, sorted) O(1) O(log n) O(log n)
Insertion (end) O(1) O(1) O(1)
Insertion (middle) O(n) O(n) O(n)
Deletion O(1) O(n) O(n)




3. Linked Lists