目录
T55-二叉树的深度(https://www.nowcoder.com/practice/435fb86331474282a3499955f0a41e8b?tpId=13&tqId=11191&tPage=2&rp=1&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking)
迭代和递归 py2
python的层次遍历
迭代 与"从上往下打印二叉树"那一题不同的是,那个只需要一个队列
这个由于要保存层数,所以需要用到next_queue这个辅助对列
#迭代
class Solution:
def TreeDepth(self, pRoot):
# write code here
if not pRoot:
return 0
queue = [pRoot]
next_queue = []
i = 0
while queue&nbs***bsp;next_queue:
i+=1
while queue:
node = queue.pop(0)
if node.left:
next_queue.append(node.left)
if node.right:
next_queue.append(node.right)
queue = next_queue
next_queue = []
return i
#递归
class Solution:
def TreeDepth(self, pRoot):
# write code here
if not pRoot:
return 0
left = self.TreeDepth(pRoot.left)
right = self.TreeDepth(pRoot.right)
return left+1 if left>right else right+1
把二叉树打印成多行
层次遍历 迭代 py2
这个就是二叉树层次遍历需要返回二维数组的情况啦
# -*- coding:utf-8 -*-
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
# 返回二维列表[[1,2],[4,5]]
def Print(self, pRoot):
# write code here
if not pRoot:
return []
res = []
queue,next_queue = [pRoot],[]
while queue or next_queue:
res.append([])
while queue:
node = queue.pop(0)
res[-1].append(node.val)
if node.left:
next_queue.append(node.left)
if node.right:
next_queue.append(node.right)
queue = next_queue
next_queue = []
return res