二叉树遍历

二叉树的遍历分为深度优先遍历（Depth First Traversal）和广度优先遍历（Breath First Traversal also called Levelorder Traversal）。其中深度优先遍历又分为先序遍历（Preorder Traversal），中序遍历（Inorder Traversal）和后续遍历（Postorder Traversal）。

Pre-order Traversal

Visit the root, traverse the left subtree, traverse the right subtree.

• recursive
• stack

In-order Traversal

Traverse the left subtree, visit the root, traverse the right subtree.

• recursive
• stack

Post-order Traversal

Traverse the left subtree, traverse the right subtree, visit the root.

• recursive
• stack