Merge Sort (out of place)

#include <iostream>
using namespace std;

// Function to merge two sorted halves of the array into a single sorted array.
void merge(int arr[], int left, int mid, int right) 
{
    int n1 = mid - left + 1;
    int n2 = right - mid;

    //temporary arrays
    int leftArr[n1], rightArr[n2];

    //copy data to temporary arrays
    for (int i = 0; i < n1; i++)
        leftArr[i] = arr[left + i];
    for (int j = 0; j < n2; j++)
        rightArr[j] = arr[mid + 1 + j];

    //merge temporary arrays back into arr[left..right]
    int i = 0, j = 0, k = left;
    while (i < n1 && j < n2) 
    {
        if (leftArr[i] <= rightArr[j]) 
        {
            arr[k] = leftArr[i];
            i++;
        } else {
            arr[k] = rightArr[j];
            j++;
        }
        k++;
    }

    //copy the remaining elements of leftArr[], if any
    while (i < n1) 
    {
        arr[k] = leftArr[i];
        i++;
        k++;
    }

    //copy the remaining elements of rightArr[], if any
    while (j < n2) 
    {
        arr[k] = rightArr[j];
        j++;
        k++;
    }
}

// Function to recursively divide the array and merge the sorted halves.
void mergeSort(int arr[], int left, int right) 
{
    if (left < right) 
    {
        int mid = left + (right - left) / 2;

        //sort first and second halves
        mergeSort(arr, left, mid);
        mergeSort(arr, mid + 1, right);

        //merge the sorted halves
        merge(arr, left, mid, right);
    }
}

// Function to initiate the merge sort process.
void processMergeSort(int arr[], int n) 
{
    if (n > 1) 
    {
        mergeSort(arr, 0, n - 1);
    }
}

void displayArray(int arr[], int n) {
    for (int i = 0; i < n; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;
}

// Function to dynamically allocate an array and fill it with random values.
void fillDynamicArrayWithRandomValues(int** arr, int* n) {
    cout << "Enter the size of the array: ";
    cin >> *n;
    *arr = new int[*n];
    srand(time(0)); // Seed for random number generation
    for (int i = 0; i < *n; i++) {
        (*arr)[i] = rand() % 1000; // Fill with random numbers between 0 and 999
    }
}

int main() {
    int* arr;
    int n;
    fillDynamicArrayWithRandomValues(&arr, &n);
    cout << "Unsorted array: ";
    displayArray(arr, n);
    processMergeSort(arr, n);
    cout << "Sorted array: ";
    displayArray(arr, n);
    delete[] arr; // Deallocate dynamically allocated memory
    return 0;
}