package LeetCode;

import java.util.*;

public class LC_107 {
    public List<List<Integer>> levelOrderBottom(TreeNode root) {
        List<List<Integer>> res = new ArrayList<>();
        if (root == null) return res;
        Queue<TreeNode> que = new LinkedList<>();
        que.add(root);
        while (!que.isEmpty()) {
            int len = que.size();
            List<Integer> res_tmp = new ArrayList<>();
            while (len > 0) {
                TreeNode p = que.poll();
                res_tmp.add(p.val);
                if (p.left != null) que.add(p.left);
                if (p.right != null) que.add(p.right);
                len--;
            }
            res.add(0,res_tmp);
        }
        //Collections.reverse(res);
        return res;
    }
}