Convert Sorted Array to Binary Search Tree

/**

 * 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) {

        if(num.length<=0) return null;

        

        TreeNode root=sort(num,0,num.length-1);

        return root;

        

        

    }

    public TreeNode sort(int[] num,int i,int j)

    {

        if(i>j) return null;

        if(i==j)

        {

            return new TreeNode(num[i]);

        }

        int mid=(i+j)>>1;

        TreeNode root=new TreeNode(num[mid]);

        root.left=sort(num,i,mid-1);

        root.right=sort(num,mid+1,j);

        

        return root;

        

        

        

        

    }

}