请用伪码帮我写一个二分归并排序算法

下面是伪代码实现：

function merge_sort(arr, left, right)
    if left < right
        mid = (left + right) / 2
        merge_sort(arr, left, mid)
        merge_sort(arr, mid+1, right)
        merge(arr, left, mid, right)

function merge(arr, left, mid, right)
    n1 = mid - left + 1
    n2 = right - mid
    L = new array[n1]
    R = new array[n2]

    for i = 0 to n1-1
        L[i] = arr[left+i]
    for j = 0 to n2-1
        R[j] = arr[mid+1+j]

    i = 0
    j = 0
    k = left

    while i < n1 and j < n2
        if L[i] <= R[j]
            arr[k] = L[i]
            i++
        else
            arr[k] = R[j]
            j++
        k++

    while i < n1
        arr[k] = L[i]
        i++
        k++

    while j < n2
        arr[k] = R[j]
        j++
        k++

其中，`merge_sort` 函数用于递归地分割数组并调用 `merge` 函数进行合并。`merge` 函数用于将两个有序数组合并成一个有序数组。最终，`merge_sort` 函数返回排序好的整个数组。