Preorder traversal: traverse the root first, then the left subtree, then the right subtree
Inorder traversal: left subtree, root, right subtree
Postorder traversal: left subtree, right subtree, root
Preorder traversal: traverse the root first, then the left subtree, then the right subtree
Inorder traversal: left subtree, root, right subtree
Postorder traversal: left subtree, right subtree, root