Merge sort

#include<bits/stdc++.h>

using namespace std;

void Merge(int *A,int p,int q,int r)
{
    int n1=q-p+1;
    int n2=r-q;
    int * L=new int[n1]; ///1 base indexing from here
    int * R=new int[n2];

    for(int i=1;i<=n1;i++)
    {
        L[i]=A[p+i-1];
    }

    for(int j=1;j<=n2;j++)
    {
        R[j]=A[q+j];
    }

    L[n1+1]=9999999;
    R[n2+1]=9999999;

    int i=1;
    int j=1;

    for(int k=p;k<=r;k++)
    {
        if(L[i]<=R[j])
        {
            A[k]=L[i];
            i++;
        }
        else
        {
            A[k]=R[j];
            j++;
        }

    }

}


void Merge_sort(int* A,int p,int r)
{
    if(p<r)
    {
        int q=int((p+r)/2);
        Merge_sort(A,p,q);
        Merge_sort(A,q+1,r);
        Merge(A,p,q,r);
    }
}

int main()
{

    int A[]={20,30,10,40,50,5,100,80};
    int z=sizeof(A)/sizeof(A[0]);


    Merge_sort(A,0,7);

    for(int i=0;i<z;i++)
        cout<<A[i]<<",";

}