文章目录
题目描述Example 1:Note:
题目思路代码
题目描述
Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.
Example 1:
Input:
3
/ \
9 20
/ \
15 7
Output: [3, 14.5, 11]
Explanation:
The average value of nodes on level 0 is 3, on level 1 is 14.5, and on level 2 is 11. Hence return [3, 14.5, 11].
Note:
The range of node’s value is in the range of 32-bit signed integer.
题目思路
这道题和429. N-ary Tree Level Order Traversal那道题很像，也是广度优先遍历，只不过那道题返回一个列表，这道题返回val的平均值。
代码
class Solution:
def averageOfLevels(self
, root
: TreeNode
) -> List
[float]:
result
= []
cur
= [root
]
nex
= []
while cur
:
sum_
= 0
for node
in cur
:
sum_
+= node
.val
if node
.left
: nex
.append
(node
.left
)
if node
.right
: nex
.append
(node
.right
)
result
.append
(sum_
/ len(cur
))
cur
= nex
nex
= []
return result
