@@ -0,0 +1,387 @@
+/**%0A * Definition for a binary tree node.%0A * public class TreeNode %7B%0A *     int val;%0A *     TreeNode left;%0A *     TreeNode right;%0A *     TreeNode(int x) %7B val = x; %7D%0A * %7D%0A */%0Aclass Solution %7B%0A    public int countNodes(TreeNode root) %7B%0A        %0A        if (root == null) %7B%0A            return 0;%0A        %7D%0A        %0A        return countNodes(root.left) + countNodes(root.right) + 1;%0A    %7D%0A%7D

add no.222