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104.二叉树的最大深度.py
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104.二叉树的最大深度.py
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# -*- coding:utf-8 -*-
# !/usr/bin/env python
import collections
# 树结点类
class TreeNode(object):
def __init__(self, val, left=None, right=None):
self.val = val
self.left = left
self.right = right
class Solution(object):
def maxDepth_dfs(self, root):
if not root:
return 0
else:
max_left = self.maxDepth_dfs(root.left)
max_right = self.maxDepth_dfs(root.right)
return max(max_left, max_right) + 1
def maxDepth_bfs(self, root):
if not root:
return 0
queue = collections.deque()
# 初始化深度为 0
node_depth = 0
# 初始化队列中的结点元素 root
queue.appendleft(root)
while queue:
# 每一层的遍历,深度 +1
node_depth += 1
# 记录每一层的结点集合
level_queue = []
for node in queue:
if node.left:
level_queue.append(node.left)
if node.right:
level_queue.append(node.right)
queue = level_queue
return node_depth
if __name__ == "__main__":
# 新建节点
root = TreeNode('A')
node_B = TreeNode('B')
node_C = TreeNode('C')
node_D = TreeNode('D')
node_E = TreeNode('E')
node_F = TreeNode('F')
node_G = TreeNode('G')
node_H = TreeNode('H')
node_I = TreeNode('I')
node_J = TreeNode('J')
# 构建二叉树
# A
# / \
# B C
# / \ / \
# D E F G
# / \
# H I
# \
# J
root.left, root.right = node_B, node_C
node_B.left, node_B.right = node_D, node_E
node_C.left, node_C.right = node_F, node_G
node_D.left, node_D.right = node_H, node_I
node_I.right = node_J
s = Solution()
print(s.maxDepth_dfs(root))
print(s.maxDepth_bfs(root))