Problem108.java

class Problem108 {

 public static void main(String[] args) {
 Problem108 p = new Problem108();
 int[] nums = {};
 System.out.println(p.sortedArrayToBST(nums));
 }

 public TreeNode sortedArrayToBST(int[] nums) {
 if (nums.length <= 0) return null;
 int root = nums.length / 2;
 TreeNode rootNode = new TreeNode(nums[root]);

 rootNode.left = assign(nums, 0, root-1);
 rootNode.right = assign(nums, root+1, nums.length-1);

 return rootNode;
 }

 TreeNode assign(int[] nums, int left, int right) {
 TreeNode rootNode = null;
 if (right >= left) {
 int root = (right+left) / 2;
 rootNode = new TreeNode(nums[root]);
 
 rootNode.left = assign(nums, left, root-1);
 rootNode.right = assign(nums, root+1, right);
 }
 return rootNode;
 }
}