๐ ๅๆ Offer 32 - III. ไปไธๅฐไธๆๅฐไบๅๆ III
2022ๅนด10ๆ10ๆฅ
- algorithm
๐ ๅๆ Offer 32 - III. ไปไธๅฐไธๆๅฐไบๅๆ III
้พๅบฆ: ๐
้ฎ้ขๆ่ฟฐ
่งฃๆณ
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public List<List<Integer>> levelOrder(TreeNode root) {
// ๆ่ทฏ๏ผ
// ๅฑๅบ้ๅ - ่พ
ๅฉ้ๅ
List<List<Integer>> res = new ArrayList<>();
if(root == null) {
return res;
}
LinkedList<TreeNode> queue = new LinkedList<>();
queue.offer(root);
boolean flag = true;
while(!queue.isEmpty()) {
int len = queue.size();
LinkedList<Integer> list = new LinkedList<>();
for(int i = 0; i < len; i ++) {
TreeNode cur = queue.poll();
if(flag) {
list.addLast(cur.val);
} else {
list.addFirst(cur.val);
}
if(cur.left != null) {
queue.offer(cur.left);
}
if(cur.right != null) {
queue.offer(cur.right);
}
}
flag = !flag;
res.add(list);
}
return res;
}
}