Insertion in array

Insertion in array 

Insertion in  array in C is Insertion operation is to insert one or more data elements into an array. Base on the requirement, a new element can be add at the beginning, end or any given index of array.

After inserting the element in the array, the positions or index location is increased but it does not mean the size of the array is increasing.

 

Diagramatic Representation:

Approach

1. Consider the x which get the element to be insert
2. secondly consider the pos word which get the position at which this element is to be insert
3. Then shift the array elements from this position to one position forward, and do this for all the other elements next to pos.
4. Insert the element x now at the position pos, as this is now empty.

Algorithm of Insertion in array

Let LA be a Linear Array with N elements and K is a positive integer such that K<=N.Following is the algorithm where ITEM is inserted into the K position of LA

1.[Initialize Counter]

   Set J=N

2.Repeat steps 3 and 4 while J>=K

3.Move jth element downward

  Set LA[J+1]=LA[J]

4.Decrease Counter

   Set J=J-1

   End of step 2 loop

5.Insert element

   Set LA[K]=ITEM

6.Reset N

   Set N=N+1

7.Exit

 

Program in C

#include <stdio.h>
 
int main()
{
    int arr[100] = { 0 };
    int i, x, pos, n = 10;
 
    for (i = 0; i < 10; i++)          // initial array of size 10
       arr[i] = i + 1;
 
                      
    for (i = 0; i < n; i++)          // print the original array
       printf("%d ", arr[i]);
       printf("\n");
 
    x = 20;                           // element to be inserted
    pos = 5;                          // position at which element is to be inserted
    n++;
 
    for (i = n-1; i >= pos; i--)         // shift elements forward
        arr[i] = arr[i - 1];
        arr[pos - 1] = x;
 
    for (i = 0; i < n; i++)             // print the updated array
        printf("%d ", arr[i]);
        printf("\n");
 
    return 0;
}

 

Output

1 2 3 4 5 6 7 8 9 10 
1 2 3 4 20 5 6 7 8 9 10

Program in CPP

#include <iostream> 
using namespace std; 
int* insertX(int n, int arr[], int x, int pos) 
{ 
int i;
 n++;
 for (i = n; i >= pos; i--) 
arr[i] = arr[i - 1]; 
arr[pos - 1] = x;
 return arr;
 } 
int main()
 { 
int arr[100] = { 0 };
 int i, x, pos, n = 10;
 for (i = 0; i < 10; i++) 
arr[i] = i + 1;
 for (i = 0; i < n; i++)
 cout << arr[i] << " ";
 cout << endl;
 x = 20;
 pos = 5;
 insertX(n, arr, x, pos); 
for (i = 0; i < n + 1; i++)
 cout << arr[i] << " "; 
cout << endl; 
return 0; 
}

 

Output

1 2 3 4 5 6 7 8 9 10
1 2 3 4 20 5 6 7 8 9 10

 

Approach

1. First consider the word “element” which  to be inserted
2.  Consider the “position”which get the position at which this element is to be insert.
3. Then Convert array to ArrayList
4. Add element at position using list.add(position, element)
5. Convert ArrayList back to array and print

Program in Java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
 
public class AddElementAtPositionInArray {
     
    private static void addElement(                               // Method to add element at position
        Integer[] arr, int element,
        int position)
    {
       
        List<Integer> list = new ArrayList<>(                   // Converting array to ArrayList
            Arrays.asList(arr));
         
        list.add(position - 1, element);                        // Adding the element at position
         
        arr = list.toArray(arr);                                // Adding the element at position
 
       
        System.out.println("Initial Array:\n"                    // Printing the original array
                        + Arrays.toString(arr));
 
        // Printing the updated array
        System.out.println("\nArray with " + element
                        + " inserted at position "
                        + position + ":\n"
                        + Arrays.toString(arr));
    }
     
    
    public static void main(String[] args)
    {
        Integer[] arr = { 1, 2, 3, 4, 5,
                        6, 7, 8, 9, 10 };
     
        int element = 20;
     
        
        int position = 5;
     
        
        addElement(arr, element, position);
    }
}

Output

Initial Array: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Array with 50 inserted at position 5:
[1, 2, 3, 4, 20, 5, 6, 7, 8, 9, 10]

 

Time complexity

O(1)

 

Also, read the Array operation 

Deletion in array

Traversing in array

Searcing in array

Updation in array