inversion of array using merge sort, C++ (gcc)

inversion of array using merge sort

long long merge(long long arr[],long long lo,long long mid,long long hi,long long n,long long &c)
{
    long long temp[n];
    long long i=lo;
    long long j=mid+1;
    long long k=lo;
    while(i<=mid && j<=hi)
    {
        if(arr[i]<=arr[j])
        {
            temp[k]=arr[i];
            i++,k++;
        }
        else if(arr[j]<arr[i])
        {
            temp[k]=arr[j];
            j++,k++;
             c+=(mid-i+1);
        }
    }
    if(i>mid)
    {
        while(j<=hi)
        {
            temp[k]=arr[j];
            j++;k++;
        }
    }
    else
    {
        while(i<=mid)
        {
            temp[k]=arr[i];
            i++,k++;
        }
    }
    for(int q=lo;q<=hi;q++)
    {
        arr[q]=temp[q];
    }
    // for(int i=0;i<n;i++)
    //   cout<<arr[i]<< " ";
    //   cout<<endl;
    return c;
}
long long  mergesort(long long arr[],long long lo,long long hi,long long n,long long &c)
{
    if(lo<hi)
    {
    
    long long mid=lo+(hi-lo)/2;
    mergesort(arr,lo,mid,n,c);
    mergesort(arr,mid+1,hi,n,c);
    merge(arr,lo,mid,hi,n,c);
    return c;
    }
}
long long int inversionCount(long long arr[], long long n)
{
    // Your Code Here
    long long c=0;
   return  mergesort(arr,0,n-1,n,c);
    
    
}


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