Convert Sorted Array to Binary Search Tree

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

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public TreeNode sortedArrayToBST(int[] num) {        TreeNode root=null;        if(num==null || num.length==0) return root;        root=convert(root,0,num.length-1,num);        return root;    }    public TreeNode convert(TreeNode node ,int left,int right,int []num){        if(left>right){            return null;        }        int mid=left+(right-left)/2;        node=new TreeNode(num[mid]);        node.left=convert(node.left,left,mid-1,num);        node.right=convert(node.right,mid+1,right,num);        return node;    }}