AverageofLevelsinBinaryTree.py

"""
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,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].
Example 2:


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


Constraints:

The number of nodes in the tree is in the range [1, 104].
-231 <= Node.val <= 231 - 1
"""


from collections import deque

# 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 averageOfLevels(self, root: TreeNode) -> List[float]:
        if not root:
            return []

        averages = []
        queue = deque([root])

        while queue:
            level_size = len(queue)
            level_sum = 0

            for i in range(level_size):
                node = queue.popleft()
                level_sum += node.val

                if node.left:
                    queue.append(node.left)
                if node.right:
                    queue.append(node.right)

            # Calculate the average for the current level
            average = level_sum / level_size
            averages.append(average)

        return averages


# Example 1
root1 = TreeNode(3, TreeNode(9), TreeNode(20, TreeNode(15), TreeNode(7)))
solution = Solution()
print(solution.averageOfLevels(root1))  # Output should be [3.0, 14.5, 11.0]

# Example 2
root2 = TreeNode(3, TreeNode(9), TreeNode(20, TreeNode(15), TreeNode(7)))
solution = Solution()
print(solution.averageOfLevels(root2))  # Output should be [3.0, 14.5, 11.0]