【稳住，can win】Python二叉树的遍历

# 前序遍历
def pre_order(root):
	if root is None:
		return 
	print(root.data)
	pre_order(root.left)
	pre_order(root.right)
	
# 中序遍历
def in_order(root):
	if root is None:
		return 
	in_order(root.left)
	print(root.data)
	in_order(root.right)

# 后序遍历
def post_order(root):
	if root is None:
		return 
	post_order(root.left)
	post_order(root.right)
	print(root.data)

利用队列可以实现非递归形式的广度优先遍历。

def bfs(root):
	queue = []
	res = []
	queue.append(root.data)
	while queue:
		sz = len(queue)
		for i in range(sz):
			node = queue.pop(0)
			res.append(node.data)
			
			if node.left:
				queue.append(node.left.data)
			if node.right:
				queue.append(node.right.data)