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| 1 | +# https://leetcode.com/problems/average-of-levels-in-binary-tree/ |
| 2 | +# 637. Average of Levels in Binary Tree |
| 3 | + |
| 4 | +from typing import Optional, List |
| 5 | +from common.leetcodeds import TreeNode |
| 6 | +from collections import deque, defaultdict |
| 7 | + |
| 8 | + |
| 9 | +class Solution: |
| 10 | + def averageOfLevels(self, root: Optional[TreeNode]) -> List[float]: |
| 11 | + queue = deque() |
| 12 | + queue.append((0, root)) |
| 13 | + result = [] |
| 14 | + count = defaultdict(int) |
| 15 | + |
| 16 | + while queue: |
| 17 | + depth, node = queue.popleft() |
| 18 | + if depth >= len(result): |
| 19 | + result.append(node.val) |
| 20 | + else: |
| 21 | + result[depth] += node.val |
| 22 | + |
| 23 | + count[depth] += 1 |
| 24 | + |
| 25 | + if node.left is not None: |
| 26 | + queue.append((depth + 1, node.left)) |
| 27 | + if node.right is not None: |
| 28 | + queue.append((depth + 1, node.right)) |
| 29 | + |
| 30 | + for idx in range(len(result)): |
| 31 | + result[idx] /= count[idx] |
| 32 | + |
| 33 | + return result |
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