[LeetCode] Convert Sorted Array to Binary Search Tree

Thought:
The middle position of the array will be the root.
All left elements will be the left subtree.
All right elements will be the right subtree.

Code:
public class Solution {
    public TreeNode sortedArrayToBST(int[] num) {
        int len = num.length;
        if(len == 0) return null;
        TreeNode root = new TreeNode(num[len/2]);
        root.left = sortedArrayToBST(Arrays.copyOfRange(num, 0, len/2));
        root.right = sortedArrayToBST(Arrays.copyOfRange(num, len/2 + 1, len));
        return root;
    }
}