Binary Tree Inorder Traversal

 1 public class Solution {
 2     public ArrayList<Integer> inorderTraversal(TreeNode root) {
 3         // IMPORTANT: Please reset any member data you declared, as
 4         // the same Solution instance will be reused for each test case.
 5         ArrayList<Integer> result = new ArrayList<Integer>();
 6         traversal(root, result);
 7         return result;
 8     }
 9     private void traversal(TreeNode root, ArrayList<Integer> list)
10     {
11         if(root == null)
12             return;
13         traversal(root.left, list);
14         list.add(root.val);
15         traversal(root.right, list);
16     }
17 }