This program merge two sorted arrays using recursion in c++ programming language.

merge_sort_recursive.cpp

//program to merge two array using recursive function
#include "iostream"
#include "conio.h"
using namespace std;

void merge_r(int a1[],int a2[],int c[],int s1,int s2,int i=0,int j=0,int k=0){

if(i<s1 && j<s2){

    if(a1[i]>a2[j]){
    c[k++]=a2[j++];

    }else{
    c[k++]=a1[i++];
    }
    merge_r(a1,a2,c,s1,s2,i,j,k);

}
else{

        if(i<s1){
            c[k++]=a1[i++];
             merge_r(a1,a2,c,s1,s2,i,j,k);
        }

        if(j<s2){
            c[k++]=a2[j++];
             merge_r(a1,a2,c,s1,s2,i,j,k);

        }

}
}
int main(){

int *a1= new int,*a2= new int,s1,s2;
int *c  =new  int;
cout<<"Size of the first array : ",cin>>s1;
cout<<"Size of the Second array : ",cin>>s2;
for (int i=0;i<s1;i++){
    cin>>a1[i];
}
for (int i=0;i<s2;i++){
    cin>>a2[i];

}
merge_r(a1,a2,c,s1,s2);

for(int i=0;i<s1+s2;i++){
    cout<<c[i]<<" ";
 }

getch();
delete []a1;
delete []a2;

}