package com.dsa.trees;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

public class LevelOrderTraversal {
    public static void main(String[] args) {
        try (BufferedReader reader = new BufferedReader(new FileReader("input.txt"))) {
            String[] elements = reader.readLine().trim().split(",");
            Queue<TreeNode> queue = new LinkedList<>();
            TreeNode root = new TreeNode(Integer.parseInt(elements[0]));
            queue.offer(root);
            int index = 1;
            while (!queue.isEmpty() && index < elements.length) {
                TreeNode node = queue.poll();
                if (!elements[index].equalsIgnoreCase("null")) {
                    node.left = new TreeNode(Integer.parseInt(elements[index]));
                    queue.offer(node.left);
                }
                index++;
                if (!elements[index].equalsIgnoreCase("null")) {
                    node.right = new TreeNode(Integer.parseInt(elements[index]));
                    queue.offer(node.right);
                }
                index++;
            }
            List<List<Integer>> list = levelOrderBottom(root);
            for (List<Integer> level : list) {
                System.out.println(level);
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static List<List<Integer>> levelOrder(TreeNode root) {
        List<List<Integer>> res = new LinkedList<>();
        if (root == null) return res;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            List<Integer> list = new LinkedList<>();
            int size = queue.size();
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                list.add(node.val);
                if (node.left != null) queue.offer(node.left);
                if (node.right != null) queue.offer(node.right);
            }
            res.add(list);
        }
        return res;
    }

    public static List<List<Integer>> levelOrderBottom(TreeNode root) {
        List<List<Integer>> res = new LinkedList<>();
        if (root == null) return res;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            List<Integer> list = new LinkedList<>();
            int size = queue.size();
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                list.add(node.val);
                if (node.left != null) queue.offer(node.left);
                if (node.right != null) queue.offer(node.right);
            }
            res.addFirst(list);
        }
        return res;
    }
}