LeetCode_108Convert Sorted Array to Binary Search Tree

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

高度平衡是指左右子树的高度最大相差1，二分检索树是，根节点的左子树的所有节点值都小于等于根节点，右子树的所有节点值都大于等于根节点，左右子树也是二分搜索树。

     public TreeNode sortedArrayToBST(int[] nums) {            int len = nums.length;            if (len == 0) {                return null;            }            return buildNodes3(nums, 0, len-1);        }     private TreeNode buildNodes3(int[] nums,int left,int right){         if (left>right) return null;         int mid = (left + right)/2;         TreeNode treeNode = new TreeNode(nums[mid]);         treeNode.left = buildNodes3(nums, left, mid-1);         treeNode.right = buildNodes3(nums, mid+1, right);         return treeNode;     }