package tree;

import java.util.ArrayList;

import java.util.LinkedList;

import java.util.Queue;

public class PrintByLevel {

    public static void main(String[] args) {

        TreeNode t1 = new TreeNode(1);

        TreeNode t2 = new TreeNode(2);

        TreeNode t3 = new TreeNode(3);

        TreeNode t4 = new TreeNode(4);

        TreeNode t5 = new TreeNode(5);

        t1.left=t2;

        t1.right=t3;

        t2.left=t4;

        t2.right=t5;

    }

    static ArrayList<ArrayList<Integer>> Print(TreeNode pRoot) {

        ArrayList<ArrayList<Integer>> re = new ArrayList<>();

        if (pRoot==null)

            return re;

        Queue<TreeNode> queue = new LinkedList<>();

        queue.add(pRoot);

        int nextLevel =0;

        int toBePrinted = 1;

        ArrayList<Integer> cuLevel = new ArrayList<>();

        while (!queue.isEmpty())

        {

            TreeNode tmp = queue.poll();

            cuLevel.add(tmp.val);

            if(tmp.left!=null)

            {

                queue.add(tmp.left);

                nextLevel++;

            }

            if(tmp.right!=null)

            {

                queue.add(tmp.right);

                nextLevel++;

            }

            toBePrinted--;

            if(toBePrinted==0)

            {

                re.add(cuLevel);

                cuLevel = new ArrayList<>();

                toBePrinted = nextLevel;

                nextLevel=0;

            }

        }

        return re;

    }

}