Merge an array of size n into another array of size m+n

Last Updated : 13 Jul, 2023

There are two sorted arrays. First one is of size m+n containing only m elements. Another one is of size n and contains n elements. Merge these two arrays into the first array of size m+n such that the output is sorted. 
Input: array with m+n elements (mPlusN[]). 
 

MergemPlusN

NA => Value is not filled/available in array mPlusN[]. There should be n such array blocks.
Input: array with n elements (N[]). 
 

MergeN


Output: N[] merged into mPlusN[] (Modified mPlusN[]) 
 

MergemPlusN_Res


 


Algorithm: 

Let first array be mPlusN[] and other array be N[]
1) Move m elements of mPlusN[] to end.
2) Start from nth element of mPlusN[] and 0th 
   element of N[] and merge them into mPlusN[].

Below is the implementation of the above algorithm : 

C++ 
// C++ program to Merge an array of 
// size n into another array of size m + n
#include <bits/stdc++.h>
using namespace std;

/* Assuming -1 is filled for the places
   where element is not available */
#define NA -1

/* Function to move m elements at 
   the end of array mPlusN[] */
void moveToEnd(int mPlusN[], int size)
{
   int j = size - 1;
   for (int i = size - 1; i >= 0; i--)
     if (mPlusN[i] != NA)
     {
        mPlusN[j] = mPlusN[i];
        j--;
     }
}

/* Merges array N[] of size n into
   array mPlusN[] of size m+n*/
void merge(int mPlusN[], int N[], int m, int n)
{
   int i = n; /* Current index of i/p part of mPlusN[]*/
   int j = 0; /* Current index of N[]*/
   int k = 0; /* Current index of output mPlusN[]*/
   while (k < (m + n))
   {
    /* Take an element from mPlusN[] if
    a) value of the picked element is smaller 
       and we have not reached end of it
    b) We have reached end of N[] */
    if ((j == n)||(i < (m + n) && mPlusN[i] <= N[j]))
    {
        mPlusN[k] = mPlusN[i];
        k++;
        i++;
    }
    else // Otherwise take element from N[]
    {
       mPlusN[k] = N[j];
       k++;
       j++;
    }
   }
}

/* Utility that prints out an array on a line */
void printArray(int arr[], int size)
{
   for (int i = 0; i < size; i++)
   cout << arr[i] << " ";

   cout << endl;
}

/* Driver code */
int main()
{
   /* Initialize arrays */
   int mPlusN[] = {2, 8, NA, NA, NA, 13, NA, 15, 20};
   int N[] = {5, 7, 9, 25};
   
   int n = sizeof(N) / sizeof(N[0]);
   int m = sizeof(mPlusN) / sizeof(mPlusN[0]) - n;

   /*Move the m elements at the end of mPlusN*/
   moveToEnd(mPlusN, m + n);

   /*Merge N[] into mPlusN[] */
   merge(mPlusN, N, m, n);

   /* Print the resultant mPlusN */
   printArray(mPlusN, m+n);

   return 0;
}
C 
// C program to Merge an array of 
// size n into another array of size m + n
#include <stdio.h>

/* Assuming -1 is filled for 
   the places where element
   is not available */
#define NA -1

/* Function to move m elements 
   at the end of array mPlusN[]
 */
void moveToEnd(int mPlusN[], int size)
{
    int i = 0, j = size - 1;
    for (i = size - 1; i >= 0; i--)
        if (mPlusN[i] != NA) {
            mPlusN[j] = mPlusN[i];
            j--;
        }
}

/* Merges array N[] of size n into array mPlusN[]
   of size m+n*/
void merge(int mPlusN[], int N[], int m, int n)
{
    int i = n; /* Current index of i/p part of mPlusN[]*/
    int j = 0; /* Current index of N[]*/
    int k = 0; /* Current index of output mPlusN[]*/
    while (k < (m + n)) 
    {
        /* Take an element from mPlusN[] if
           a) value of the picked element is smaller and we
           have not reached end of it
           b) We have reached end of N[] */
        if ((j == n)|| (i < (m + n)
             && mPlusN[i] <= N[j])) 
        {
            mPlusN[k] = mPlusN[i];
            k++;
            i++;
        }
        else // Otherwise take element from N[]
        {
            mPlusN[k] = N[j];
            k++;
            j++;
        }
    }
}

/* Utility that prints out an array on a line */
void printArray(int arr[], int size)
{
    int i;
    for (i = 0; i < size; i++)
        printf("%d ", arr[i]);

    printf("\n");
}

/* Driver code */
int main()
{
    /* Initialize arrays */
    int mPlusN[] = { 2, 8, NA, NA, NA, 13, NA, 15, 20 };
    int N[] = { 5, 7, 9, 25 };
    int n = sizeof(N) / sizeof(N[0]);
    int m = sizeof(mPlusN) / sizeof(mPlusN[0]) - n;

    /*Move the m elements at the end of mPlusN*/
    moveToEnd(mPlusN, m + n);

    /*Merge N[] into mPlusN[] */
    merge(mPlusN, N, m, n);

    /* Print the resultant mPlusN */
    printArray(mPlusN, m + n);

    return 0;
}
Java 
// Java program to Merge an array of 
// size n into another array of size m + n

class MergeArrays {
    /* Function to move m 
       elements at the end of array
     * mPlusN[] */
    void moveToEnd(int mPlusN[], int size)
    {
        int i, j = size - 1;
        for (i = size - 1; i >= 0; i--) {
            if (mPlusN[i] != -1) {
                mPlusN[j] = mPlusN[i];
                j--;
            }
        }
    }

    /* Merges array N[] of 
       size n into array mPlusN[]
       of size m+n*/
    void merge(int mPlusN[], int N[], int m, int n)
    {
        int i = n;

        /* Current index of i/p part of mPlusN[]*/
        int j = 0;

        /* Current index of N[]*/
        int k = 0;

        /* Current index of output mPlusN[]*/
        while (k < (m + n))
        {
            /* Take an element from mPlusN[] if
            a) value of the picked element is smaller and we
            have not reached end of it b) We have reached
            end of N[] */
            if ((i < (m + n) && mPlusN[i] <= N[j])
                || (j == n)) {
                mPlusN[k] = mPlusN[i];
                k++;
                i++;
            }
            else // Otherwise take element from N[]
            {
                mPlusN[k] = N[j];
                k++;
                j++;
            }
        }
    }

    /* Utility that prints out an array on a line */
    void printArray(int arr[], int size)
    {
        int i;
        for (i = 0; i < size; i++)
            System.out.print(arr[i] + " ");

        System.out.println("");
    }

    // Driver Code
    public static void main(String[] args)
    {
        MergeArrays mergearray = new MergeArrays();

        /* Initialize arrays */
        int mPlusN[] = { 2, 8, -1, -1, -1, 13, -1, 15, 20 };
        int N[] = { 5, 7, 9, 25 };
        int n = N.length;
        int m = mPlusN.length - n;

        /*Move the m elements at the end of mPlusN*/
        mergearray.moveToEnd(mPlusN, m + n);

        /*Merge N[] into mPlusN[] */
        mergearray.merge(mPlusN, N, m, n);

        /* Print the resultant mPlusN */
        mergearray.printArray(mPlusN, m + n);
    }
}

// This code has been contributed by Mayank Jaiswal
Python3 
# Python program to Merge an array of 
# size n into another array of size m + n

NA = -1

# Function to move m elements
# at the end of array mPlusN[]


def moveToEnd(mPlusN, size):

    i = 0
    j = size - 1
    for i in range(size-1, -1, -1):
        if (mPlusN[i] != NA):

            mPlusN[j] = mPlusN[i]
            j -= 1

# Merges array N[]
# of size n into array mPlusN[]
# of size m+n


def merge(mPlusN, N, m, n):

    i = n  # Current index of i/p part of mPlusN[]
    j = 0  # Current index of N[]
    k = 0  # Current index of output mPlusN[]
    while (k < (m+n)):

        # Take an element from mPlusN[] if
        # a) value of the picked
        # element is smaller and we have
        # not reached end of it
        # b) We have reached end of N[] */
        if ((j == n) or (i < (m+n) and mPlusN[i] <= N[j])):

            mPlusN[k] = mPlusN[i]
            k += 1
            i += 1

        else:  # Otherwise take element from N[]

            mPlusN[k] = N[j]
            k += 1
            j += 1

# Utility that prints
# out an array on a line


def printArray(arr, size):

    for i in range(size):
        print(arr[i], " ", end="")

    print()


# Driver function to
# test above functions

# Initialize arrays
mPlusN = [2, 8, NA, NA, NA, 13, NA, 15, 20]
N = [5, 7, 9, 25]
n = len(N)

m = len(mPlusN) - n

# Move the m elements
# at the end of mPlusN
moveToEnd(mPlusN, m+n)

# Merge N[] into mPlusN[]
merge(mPlusN, N, m, n)

# Print the resultant mPlusN
printArray(mPlusN, m+n)

# This code is contributed
# by Anant Agarwal.
C# 
// C# program to Merge an array of
// size n into another array of size m + n
using System;

class GFG {
    /* Function to move m elements at
       the end of array mPlusN[] */
    public virtual void moveToEnd(int[] mPlusN, int size)
    {
        int i, j = size - 1;
        for (i = size - 1; i >= 0; i--) 
        {
            if (mPlusN[i] != -1) {
                mPlusN[j] = mPlusN[i];
                j--;
            }
        }
    }

    /* Merges array N[] of size n
       into array mPlusN[] of size m+n*/
    public virtual void merge(int[] mPlusN,
                              int[] N, int m,
                              int n)
    {
        int i = n;

        /* Current index of i/p
           part of mPlusN[]*/
        int j = 0;

        /* Current index of N[]*/
        int k = 0;

        /* Current index of output mPlusN[]*/
        while (k < (m + n))
        {
            /* Take an element from mPlusN[] if
            a) value of the picked element is smaller
               and we have not reached end of it
            b) We have reached end of N[] */
            if ((j == n)(i < (m + n) 
                && mPlusN[i] <= N[j]))
            {
                mPlusN[k] = mPlusN[i];
                k++;
                i++;
            }
            else // Otherwise take element from N[]
            {
                mPlusN[k] = N[j];
                k++;
                j++;
            }
        }
    }

    /* Utility that prints out
       an array on a line */
    public virtual void printArray(int[] arr, int size)
    {
        int i;
        for (i = 0; i < size; i++) {
            Console.Write(arr[i] + " ");
        }

        Console.WriteLine("");
    }

    // Driver Code
    public static void Main(string[] args)
    {
        GFG mergearray = new GFG();

        /* Initialize arrays */
        int[] mPlusN = new int[] { 2,  8,  -1, -1, -1,
                                   13, -1, 15, 20 };
        int[] N = new int[] { 5, 7, 9, 25 };
        int n = N.Length;
        int m = mPlusN.Length - n;

        /*Move the m elements at the
          end of mPlusN*/
        mergearray.moveToEnd(mPlusN, m + n);

        /*Merge N[] into mPlusN[] */
        mergearray.merge(mPlusN, N, m, n);

        /* Print the resultant mPlusN */
        mergearray.printArray(mPlusN, m + n);
    }
}

// This code is contributed by Shrikant13
PHP 
<?php
// PHP program to Merge an array 
// of size n into another array 
// of size m + n

/* Assuming -1 is filled for 
the places where element is 
not available */
$NA = -1;

/* Function to move m elements 
at the end of array mPlusN[] */
function moveToEnd(&$mPlusN, $size)
{
    global $NA;
    $j = $size - 1;
    for ($i = $size - 1; $i >= 0; $i--)
        if ($mPlusN[$i] != $NA)
        {
            $mPlusN[$j] = $mPlusN[$i];
            $j--;
        }
}

/* Merges array N[] of size n 
into array mPlusN[] of size m+n*/
function merge(&$mPlusN, &$N, $m, $n)
{
    $i = $n; /* Current index of i/p 
                part of mPlusN[]*/
    $j = 0;  /* Current index of N[]*/
    $k = 0;  /* Current index of
                output mPlusN[]*/
    while ($k < ($m + $n))
    {
        /* Take an element from mPlusN[] if
        a) value of the picked element 
           is smaller and we have not
           reached end of it
        b) We have reached end of N[] */
        if (($j == $n) || ($i < ($m + $n) &&
             $mPlusN[$i] <= $N[$j]))
        {
            $mPlusN[$k] = $mPlusN[$i];
            $k++;
            $i++;
        }
        else // Otherwise take element from N[]
        {
            $mPlusN[$k] = $N[$j];
            $k++;
            $j++;
        }
}
}

/* Utility that prints out
   an array on a line */
function printArray(&$arr, $size)
{
    for ($i = 0; $i < $size; $i++)
    echo $arr[$i] . " ";
    
    echo "\n";
}

// Driver Code

/* Initialize arrays */
$mPlusN = array(2, 8, $NA, $NA, $NA,
                13, $NA, 15, 20);
$N = array(5, 7, 9, 25);
    
$n = sizeof($N);
$m = sizeof($mPlusN) - $n;

/* Move the m elements 
   at the end of mPlusN*/
moveToEnd($mPlusN, $m + $n);

/* Merge N[] into mPlusN[] */
merge($mPlusN, $N, $m, $n);

/* Print the resultant mPlusN */
printArray($mPlusN, $m+$n);

// This code is contributed
// by ChitraNayal
?>
JavaScript 
<script>
// Javascript program to Merge an array of 
// size n into another array of size m + n

    /* Function to move m 
       elements at the end of array
     * mPlusN[] */
    function moveToEnd(mPlusN,size)
    {
        let i = 0;
        let j = size - 1;
        for (i = size - 1; i >= 0; i--)
        {
            if (mPlusN[i] != -1)
            {
                mPlusN[j] = mPlusN[i];
                j--;
            }
        }
    }
    
    /* Merges array N[] of 
       size n into array mPlusN[]
       of size m+n*/
    function merge(mPlusN, N, m, n)
    {
        let i = n;
        
        /* Current index of i/p part of mPlusN[]*/
        let j = 0;
        
        /* Current index of N[]*/
        let k = 0;
        
        /* Current index of output mPlusN[]*/
        while (k < (m + n))
        {
        
            /* Take an element from mPlusN[] if
            a) value of the picked element is smaller and we
            have not reached end of it b) We have reached
            end of N[] */
            if ((i < (m + n) && mPlusN[i] <= N[j]) || (j == n))
            {
                mPlusN[k] = mPlusN[i];
                k++;
                i++;
            }
            else    // Otherwise take element from N[]
            {
                mPlusN[k] = N[j];
                k++;
                j++;
            }
        }
    }
    
    /* Utility that prints out an array on a line */
    function printArray(arr,size)
    {
        let i = 0;
        for (i = 0; i < size; i++)
        {
            document.write(arr[i] + " ");
        }
        document.write("\n");
    }
    
    // Driver Code   
     /* Initialize arrays */
    let mPlusN = [2, 8, -1, -1, -1, 13, -1, 15, 20];
    let N = [ 5, 7, 9, 25]
    let n = N.length;
    let m = mPlusN.length - n;
    
    /*Move the m elements at the end of mPlusN*/
    moveToEnd(mPlusN, m + n);
    
    /*Merge N[] into mPlusN[] */
    merge(mPlusN, N, m, n);
    
    /* Print the resultant mPlusN */
    printArray(mPlusN, m + n);
    
    // This code is contributed by avanitrachhadiya2155
</script>

Output
2 5 7 8 9 13 15 20 25

Time Complexity: O(m+n)
Auxiliary Space: O(1)

 

Please write a comment if you find any bug in the above program or a better way to solve the same problem.

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