#2265

Count Nodes Equal to Average of Subtree

pupil · 380 · lc medium +24 · verified · 86.8% accepted · 2,355 likes · top 98%

Description

Given the root of a binary tree, return the number of nodes whose value equals the integer average of all values in their subtree.

Note:

- The average of n elements uses floor (integer) division.

- A node's subtree consists of the node and all its descendants.

Example 1:

Input: root = [4,8,5,0,1,null,6]

Output: 5

Explanation:

For the node with value 4: The average of its subtree is (4 + 8 + 5 + 0 + 1 + 6) / 6 = 24 / 6 = 4.

For the node with value 5: The average of its subtree is (5 + 6) / 2 = 11 / 2 = 5.

For the node with value 0: The average of its subtree is 0 / 1 = 0.

For the node with value 1: The average of its subtree is 1 / 1 = 1.

For the node with value 6: The average of its subtree is 6 / 1 = 6.

Example 2:

Input: root = [1]

Output: 1

Explanation: For the node with value 1: The average of its subtree is 1 / 1 = 1.

Code

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def averageOfSubtree(self, root: TreeNode) -> int:

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def averageOfSubtree(self, root: TreeNode) -> int: