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111 lines (86 loc) · 2.64 KB
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# -*- coding: utf-8 -*-
__author__ = 'xiaoxiaoming'
from typing import Optional, List
class TreeNode():
def __init__(self, value):
self.val = value
self.left = None
self.right = None
# 前序遍历
def pre_order(root: Optional[TreeNode]):
if root:
yield root.val
yield from pre_order(root.left)
yield from pre_order(root.right)
# 中序遍历
def in_order(root: Optional[TreeNode]):
if root:
yield from in_order(root.left)
yield root.val
yield from in_order(root.right)
# 后序遍历
def post_order(root: Optional[TreeNode]):
if root:
yield from post_order(root.left)
yield from post_order(root.right)
yield root.val
from collections import deque
# 层级遍历
def layer_order(root: TreeNode):
if not root: return
queue = deque([root])
while queue:
e: TreeNode = queue.popleft()
yield e.val
if e.left: queue.append(e.left)
if e.right: queue.append(e.right)
def level_order(root: TreeNode) -> List[List]:
levels = []
if not root:
return levels
level = 0
queue = deque([root])
while queue:
levels.append([])
for i in range(len(queue)):
node = queue.popleft()
levels[level].append(node.val)
if node.left:
queue.append(node.left)
if node.right:
queue.append(node.right)
level += 1
return levels
# 根节点高度=max(左子树高度，右子树高度)+1
def get_level(node: TreeNode) -> int:
if node is None: return 0
return max(get_level(node.left), get_level(node.right)) + 1
if __name__ == "__main__":
root = TreeNode("root")
l1 = TreeNode("l1")
r1 = TreeNode("r1")
l1_l2 = TreeNode("l1_l2")
l1_r2 = TreeNode("l1_r2")
r1_l2 = TreeNode("r1_l2")
r1_r2 = TreeNode("r1_r2")
l1_l2_l3 = TreeNode("l1_l2_l3")
l1_l2_r3 = TreeNode("l1_l2_r3")
l1_r2_l3 = TreeNode("l1_r2_l3")
l1_r2_r3 = TreeNode("l1_r2_r3")
r1_l2_l3 = TreeNode("r1_l2_l3")
r1_l2_r3 = TreeNode("r1_l2_r3")
r1_r2_l3 = TreeNode("r1_r2_l3")
r1_r2_r3 = TreeNode("r1_r2_r3")
root.left, root.right = l1, r1
l1.left, l1.right = l1_l2, l1_r2
r1.left, r1.right = r1_l2, r1_r2
l1_l2.left, l1_l2.right = l1_l2_l3, l1_l2_r3
l1_r2.left, l1_r2.right = l1_r2_l3, l1_r2_r3
r1_l2.left, r1_l2.right = r1_l2_l3, r1_l2_r3
r1_r2.left, r1_r2.right = r1_r2_l3, r1_r2_r3
print(list(pre_order(root)))
print(list(in_order(root)))
print(list(post_order(root)))
print(list(layer_order(root)))
print(level_order(root))
print(get_level(root))