[LeetCode]#637. Average of Levels in Binary Tree

Environment: Python 3.8

Key technique: binarytree, Node, collections, deque

Given the root of a binary tree, return the average value of the nodes on each level in the form of an array. Answers within 10-5 of the actual answer will be accepted.

Example 1:

Input: root = [3,9,20,null,15,7]
Output: [3.00000,14.50000,11.00000]
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].

Analysis:

  1. Use collections.deque()

Solution:

from binarytree import Node
root = Node(3)
root.left=Node(9)
root.right=Node(20)
root.right.left=Node(15)
root.right.right=Node(7)
# Getting binary tree
print('Binary tree :', root)
import collectionsclass Solution(object):
def averageOfLevels(self, root):
queue = collections.deque()
ans = []
queue.append(root)
while queue:
size = len(queue)
temp = []
for _ in range(size):
node = queue.popleft()
if not node:
continue
temp.append(node.val)
queue.append(node.left)
queue.append(node.right)
if temp:
ans.append(sum(temp) / float(len(temp)))
return ans

Submissions:

Reference:

Note: Not so good for node.

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