Bookshelves ZCO

#include<bits/stdc++.h>
using namespace std;
void merge(long a[],long l,long m,long r)
{
    long n1=m-l+1;
    long n2=r-m;

    long L[n1],R[n2];

    for(long i=0;i<n1;i++)
    L[i]=a[i+l];
    for(long i=0;i<n2;i++)
    R[i]=a[m+1+i];

    long p=0,q=0;

    while(p<n1 && q<n2)
    if(L[p]<R[q])
    a[l++]=L[p++];
    else
    a[l++]=R[q++];

    while(p<n1)
    a[l++]=L[p++];
    while(q<n2)
    a[l++]=R[q++];
}
void mergeSort(long a[],long l,long r)
{
    if(l<r)
    {
        long m=l+(r-l)/2;
        mergeSort(a,l,m);
        mergeSort(a,m+1,r);
        merge(a,l,m,r);
    }
}
int main()
{
    long n,k;
    cin>>n>>k;
    long a[100005],b[100005];
    for(long i=0;i<n;i++)
    cin>>a[i];
    for(long i=0;i<n;i++)
    cin>>b[i];
    mergeSort(a,0,n-1);
    mergeSort(b,0,n-1);
    if(b[n-1]<a[n-1])
        for(long i=0;i<n;i++)
        {
            long temp=a[i];
            a[i]=b[i];
            b[i]=temp;
        }
    for(long z=0;z<k;z++)
    {
        if(b[0]>=a[n-1])
        break;

        long t1=a[n-1],t2=b[0];


        long pos;
        if(a[0]>t2)
            pos=0;
        else if(a[n-2]<t2)
            pos=n-1;
        else
            for(pos=1;pos<n;pos++)
                if(t2>=a[pos-1]&&t2<=a[pos])
                break;
        for(long i=n-1;i>pos;i--)
            a[i]=a[i-1];
            a[pos]=t2;


        for(long i=0;i<n-1;i++)
            b[i]=b[i+1];
        if(b[0]>t1)
            pos=0;
        else if(b[n-2]<t1)
            pos=n-1;
        else
            for(pos=1;pos<n;pos++)
            if(t1>=b[pos-1]&&t1<=b[pos])
            break;
        for(long i=n-1;i>pos;i--)
        b[i]=b[i-1];
        b[pos]=t1;
    }
    cout<<a[n-1]+b[n-1];
    return 0;
}