from __future__ import annotations
from typing import Union
from collections import deque
class TreeNode:
def __init__(self, value, l_node: TreeNode = None, r_node: TreeNode = None):
self.value = value
self.l_node = l_node
self.r_node = r_node
def gen_tree(values: list) -> Union[TreeNode, None]:
if not values:
return None
iter_value = iter(values)
root = TreeNode(next(iter_value))
d = deque()
d.append(root)
while 1:
head = d.popleft()
try:
head.l_node = TreeNode(next(iter_value))
d.append(head.l_node)
head.r_node = TreeNode(next(iter_value))
d.append(head.r_node)
except StopIteration:
break
return root
def pre_traverse_tree(node: TreeNode):
if node is None:
return
yield node.value
yield from pre_traverse_tree(node.l_node)
yield from pre_traverse_tree(node.r_node)
def in_traverse_tree(node: TreeNode):
if node is None:
return
yield from pre_traverse_tree(node.l_node)
yield node.value
yield from pre_traverse_tree(node.r_node)
def post_traverse_tree(node: TreeNode):
if node is None:
return
yield from pre_traverse_tree(node.l_node)
yield from pre_traverse_tree(node.r_node)
yield node.value
tree = gen_tree(list(range(10)))
print(list(pre_traverse_tree(tree)))
print(list(in_traverse_tree(tree)))
print(list(post_traverse_tree(tree)))
