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637. Average of Levels in Binary Tree
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.
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/**
* @author D瓜哥 · https://www.diguage.com
* @since 2024-06-14
*/
public List<Double> averageOfLevels(TreeNode root) {
if (root == null) {
return Collections.emptyList();
}
List<Double> result = new ArrayList<>();
Deque<TreeNode> levels = new LinkedList<>();
levels.offer(root);
while (!levels.isEmpty()) {
int size = levels.size();
double sum = 0.0;
for (int i = 0; i < size; i++) {
TreeNode node = levels.poll();
sum += node.val;
if (node.left != null) {
levels.offer(node.left);
}
if (node.right != null) {
levels.offer(node.right);
}
}
result.add(sum / size);
}
return result;
}