Convert Sorted Array to Binary Search Tree

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

给定一个排好序的数组，构造一颗平衡的二叉搜索树。我们可以每次都取数组的中间点作为当前子树的根节点，递归完成。代码如下：

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode sortedArrayToBST(int[] nums) {
        if(nums == null || nums.length == 0) return null;
        int l = 0; 
        int r = nums.length - 1;
        int m = l + (r - l) / 2;
        TreeNode root = new TreeNode(nums[m]);
        root.left = sortedArrayToBST(Arrays.copyOfRange(nums, 0, m));
        root.right = sortedArrayToBST(Arrays.copyOfRange(nums, m + 1, nums.length));
        return root;
    }
}