/
AverageOfLevels.java
53 lines (44 loc) · 1.47 KB
/
AverageOfLevels.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
// https://leetcode.com/problems/average-of-levels-in-binary-tree/
class Solution {
// Do a BFS, but during each iteration, empty the queue totally,
// adding its children in a new queue and using that queue further.
public List<Double> averageOfLevels(TreeNode root) {
List<Double> res = new ArrayList<>();
Deque<TreeNode> queue = new ArrayDeque<>();
queue.add(root);
while (!queue.isEmpty()) {
Deque<TreeNode> newQueue = new ArrayDeque<>();
double sum = 0;
int count = 0;
while (!queue.isEmpty()) {
TreeNode first = queue.pollFirst();
sum += first.val;
count++;
if (first.left != null){
newQueue.add(first.left);
}
if (first.right != null){
newQueue.add(first.right);
}
}
res.add(sum/count);
queue = newQueue;
}
return res;
}
}