Description

Merge of two array means copy the elements of first and second array into third array.
Compare the corresponding elements of the both array, copy the element into third array
from first and second array which is smaller. If the elements of one array become over
copy the all elements from another array into third array.

C/C++

/* C program to merge two sorted array*/
//Save it as MergeTwoSortedArray.c

#include<stdio.h>
int main(){

    int i, firstSize, secondSize, firstIndex=0, secondIndex=0, index=0;

    printf("Enter the size of first array : ");
    scanf("%d",&firstSize);

    int firstArray[firstSize];

    printf("Enter the elements of first array : ");
    for(i=0;i<firstSize;i++){
        scanf("%d",&firstArray[i]);
    }

    printf("Enter the size of second array : ");
    scanf("%d",&secondSize);

    int secondArray[secondSize];

    printf("Enter the elements of second array : ");
    for(i=0;i<secondSize;i++){
        scanf("%d",&secondArray[i]);
    }

     /* Size of merged array is the sum of size of first
        array and second array*/
    int sizeMergeArray = firstSize + secondSize;
    int mergeArray[sizeMergeArray];

    /* Compare the corresponding element of the both the array,copy
     	the element into third array from either first array or second array which is samaller */
    while(firstIndex < firstSize && secondIndex < secondSize){

        if(firstArray[firstIndex] < secondArray[secondIndex]){
            mergeArray[index] = firstArray[firstIndex];
            firstIndex++;
        }
        else{
            mergeArray[index] = secondArray[secondIndex];
            secondIndex++;
        }
        index++;
    }
    /* If elements of first array is copied but still second array has some elements */
    if(firstIndex == firstSize){
        while(secondIndex < secondSize){
            mergeArray[index] = secondArray[secondIndex];
            secondIndex++;
            index++;
        }
    }
    /* If elements of second array is copied but still first array has some elements */
    if(secondIndex == secondSize){
        while(firstIndex < firstSize){
            mergeArray[index] = firstArray[firstIndex];
            firstIndex++;
            index++;
        }
    }
    // Finally print new array after merge of two array
    printf("The merged array is : ");
    for(i=0;i<sizeMergeArray;i++){
        printf("%d ",mergeArray[i]);
    }

    return 0;
}

Input:
Enter the size of first array : 5
Enter the elements of first array : 2
5
8
11
14
Enter the size of second array : 4
Enter the elements of second array : 7
10
13
16
Output:
The merged array is : 2 5 7 8 10 11 13 14 16

Java

/*Java program to merge two sorted array*/
//Save it as MergeTwoSortedArray.java


import java.io.*;
import java.util.Scanner;

public class MergeTwoSortedArray {

    public static void main(String[] args) {
        
        Scanner scanner = new Scanner(System.in);
        
        int i, firstSize, secondSize, firstIndex=0, secondIndex=0, index=0;

        System.out.println("Enter the size of first array : ");
        firstSize = scanner.nextInt();

        int firstArray[] = new int[firstSize];

        System.out.println("Enter the elements of first array : ");
        for(i=0;i<firstSize;i++){
        	firstArray[i] = scanner.nextInt();
        }

        System.out.println("Enter the size of second array : ");
        secondSize = scanner.nextInt();

        int secondArray[] = new int[secondSize];

        System.out.println("Enter the elements of second array : ");
        for(i=0;i<secondSize;i++){
            secondArray[i] = scanner.nextInt();
        }
        
            /* Size of merged array is the sum of size of first
            array and second array*/
        int sizeMergeArray = firstSize + secondSize;
        int mergeArray[] = new int[sizeMergeArray];

           /* Compare the corresponding element of the both the array,copy 
        the element into third array from either first array or second array which is samaller */
        while(firstIndex < firstSize && secondIndex < secondSize){

            if(firstArray[firstIndex] < secondArray[secondIndex]){
                mergeArray[index] = firstArray[firstIndex];
                firstIndex++;
            }
            else{
                mergeArray[index] = secondArray[secondIndex];
                secondIndex++;
            }
            index++;
        }

            /* If elements of first array is copied but still second array has some elements */
        if(firstIndex == firstSize){
            while(secondIndex < secondSize){
                mergeArray[index] = secondArray[secondIndex];
                secondIndex++;
                index++;
            }
        }

            /* If elements of second array is copied but still first array has some elements */
        if(secondIndex == secondSize){
            while(firstIndex < firstSize){
                mergeArray[index] = firstArray[firstIndex];
                firstIndex++;
                index++;
            }
        }
            // Finally print new array after merge of two array
        System.out.println("The merged array is : ");
        for(i=0;i<sizeMergeArray;i++){
            System.out.print(mergeArray[i]+ " ");
        }
    }
}

Input:
Enter the size of first array : 5
Enter the elements of first array : 2
5
8
11
14
Enter the size of second array : 4
Enter the elements of second array : 7
10
13
16
Output:
The merged array is : 2 5 7 8 10 11 13 14 16

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