Coursera Algorithms week4 基础标签表 练习测验：Inorder traversal with constant extra space

 1 public void traverse(BST<Key,Value> bst) {
 2     traverse(bst.root.left, bst.root);
 3 }
 4 
 5 private void traverse(Node current, Node parent) {
 6     while (current != null) {
 7         if (parent != null) {
 8             parent.left = current.right;
 9             current.right = parent;
10         }
11         if (current.left != null) {
12             parent = current;
13             current = current.left;
14         } else {
15             System.out.println(current.key);
16             current = current.right;
17             parent = null;
18         }
19     }
20 }