-
Notifications
You must be signed in to change notification settings - Fork 1
/
BinaryTreeLevelOrderTraversal.java
39 lines (36 loc) · 1.13 KB
/
BinaryTreeLevelOrderTraversal.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
/**
* 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;
* }
* }
*/
class Solution {
public List<List<Integer>> levelOrder(TreeNode root) {
List<List<Integer>> result = new ArrayList<>();
if(root == null) return result;
Queue<TreeNode> queue = new LinkedList<>();
queue.offer(root);
while(queue.size() > 0){
LinkedList<TreeNode> nextLevel = new LinkedList<>();
List<Integer> level = new ArrayList<>();
while(queue.size() > 0){
TreeNode node = queue.poll();
level.add(node.val);
if(node.left != null) nextLevel.add(node.left);
if(node.right != null) nextLevel.add(node.right);
}
result.add(level);
queue = nextLevel;
}
return result;
}
}