Insertion

7. Insertion in Array

Insertion in an array means adding a new element at a specific position in the array. Since arrays have a fixed size (in most languages), insertion requires shifting elements to create space.

1. What is Insertion in Array?

Insertion is the process of placing a new element at a given index in an array while maintaining the order of existing elements.

Example:

• Array: [10, 20, 30, 40]
• Insert 25 at index 2
• Result: [10, 20, 25, 30, 40]

2. Why Insertion Requires Shifting

Arrays store elements in continuous memory locations. So, when you insert an element in the middle, you must shift existing elements to the right.

3. Types of Insertion in Array

• Insertion at Beginning – Add element at index 0
• Insertion at Specific Position – Add element at given index
• Insertion at End – Add element at last position

4. Insertion at the End

This is the simplest form of insertion.

Example:

• Array: [10, 20, 30]
• Insert: 40
• Result: [10, 20, 30, 40]

5. Insertion at Beginning

All elements must be shifted to the right to create space at index 0.

Example:

• Array: [10, 20, 30]
• Insert: 5
• Result: [5, 10, 20, 30]

6. Insertion at Specific Position

This is the most important type of insertion.

Example:

• Array: [10, 20, 30, 40]
• Insert 25 at index 2
• Step 1: Shift 30 and 40 to right
• Step 2: Place 25 at index 2
• Result: [10, 20, 25, 30, 40]

7. Algorithm for Insertion

8. Time Complexity of Insertion

Time complexity depends on the position of insertion:

• At End: O(1)
• At Beginning: O(n)
• At Middle: O(n)

9. Advantages and Disadvantages

Advantages

• Simple to implement
• Direct memory access
• Fast access using index

Disadvantages

• Shifting elements is costly
• Fixed size in static arrays
• Insertion is slow for large data

Final Insight