二叉樹的中序遍歷和後序遍歷

class Node:
	def __init__(self, val):
		self.val = val
		self.left, self.right = None, None
class Tree:
	def create_tree(self, pre, mid):
		if pre:
			root_val = pre[0]
			root_val_index_mid = mid.index(root_val)
			root = Node(root_val)
			root.left = self.create_tree(pre[1:root_val_index_mid+1], mid[:root_val_index_mid])
			root.right = self.create_tree(pre[root_val_index_mid+1:], mid[root_val_index_mid+1:])
		else:
			return None
		return root

	def print_tree(self, root):
		nodes = [root]
		while nodes:
			node = nodes.pop(0)
			print(node.val)
			if node.left:
				nodes.append(node.left)
			if node.right:
				nodes.append(node.right)

	def mid_series(self, root):
		'''中序遍歷'''
		stack, stack2 = [], []
		node = root
		while node or stack:
			if node:
				stack.append(node)
				node = node.left
			else:
				node = stack.pop()
				stack2.append(node.val)
				node = node.right
		print(stack2)

	def back_series(self, root):
		'''後序遍歷'''
		stack, stack2 = [root], []
		while stack:
			node = stack.pop()
			stack2.insert(0, node.val)
			if node.left:
				stack.append(node.left)
			if node.right:
				stack.append(node.right)

		print(stack2)


tree = Tree()
root = tree.create_tree(['1', '2', '4', '3', '5', '6'], ['2', '4', '1', '5', '3', '6'])
# tree.print_tree(root)
tree.mid_series(root)
tree.back_series(root)