DSA Series - Chapter on Arrays

Introduction

• Welcome to the Complete DSA Series.
• Today’s chapter focuses on Arrays.
• Arrays are the first data structure we will study.

Data Structures and Algorithms

• Data Structures:

  • Structures in programming used to store data.
  • Essential for building real-life systems (websites, apps, software).
  • Data is the fuel for development and programming.

• Algorithms:

  • Efficient operations performed on data.
  • Examples include searching and sorting data in data structures.

What is an Array?

• Arrays help store multiple variables of the same type in a single structure.
• Example: Storing marks of multiple students.
  • Instead of creating multiple variables (e.g., mark1, mark2, etc.), an array can hold all values together.
  • An array can be visualized as a block of data.

Properties of Arrays

• Can store the same type of data (e.g., all integers).
• Data stored contiguously in memory.
• Arrays are linear structures, meaning data is arranged in a line.

Creating an Array

• Syntax for creating an array:

  int marks[5];  
  

• To initialize an array with values:

  int marks[] = {99, 100, 54, 36, 88};  
  

• Array size can be determined using the sizeof operator.

Accessing Array Data

• Access array elements using indices.
• Indices start from 0 to size-1.
• Example: marks[0] gives access to the first element.

Looping through Arrays

• Use loops for operations on arrays.
• Example: Printing elements using a for loop:

  for (int i = 0; i < size; i++) {  
      cout << marks[i];  
  }  
  

Finding Minimum and Maximum

• To find min/max in an array, iterate through each element and compare.

Linear Search Algorithm

• A method to find a target value in an array by checking each element sequentially.
• Returns the index of the found element or -1 if not found.
• Time complexity: O(n)

Reversing an Array

• Reverse the order of elements using the two-pointer approach.
• Swap elements from the front and back until the pointers meet.

Homework Problems

1. Write a function to calculate the sum and product of all numbers in an array.
2. Write a function to swap the maximum and minimum numbers of an array.
3. Write a function to print all unique values in an array.
4. Write a function to print the intersection of two arrays.

Conclusion

• Understanding arrays is fundamental in DSA.
• Next chapter will cover vectors, which are similar to arrays but with additional features.
• The journey of learning data structures and algorithms has begun.