题目描述
比较简单的一道题目,需要注意的是要将sum的类型改成long这样就不会溢出了,否则测试用例会出现-1这个bug:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public List<Double> averageOfLevels(TreeNode root) {
List<Double> list = new ArrayList<>();
Deque<TreeNode> tem = new LinkedList<>();
tem.offer(root);
while (!tem.isEmpty()) {
int size = tem.size();
long sum = 0;
for (int i = 0; i < size; i++) {
TreeNode node = tem.poll();
sum+=node.val;
if(node.left != null){
tem.offer(node.left);
}
if(node.right != null){
tem.offer(node.right);
}
}
list.add((double)sum/size);
}
return list;
}
}