把二叉树打印成多行

Description：从上到下按层打印二叉树，同一层结点从左至右输出。每一层输出一行。

import java.util.ArrayList;
import java.util.LinkedList;

/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    ArrayList<ArrayList<Integer> > Print(TreeNode root) {
		ArrayList<ArrayList<Integer>> list = new ArrayList<>();
        if (root == null)
            return list;
        int curCount = 1;
        int nextCount = 0;
        LinkedList<TreeNode> q = new LinkedList<>();
        q.offer(root);
        ArrayList<Integer> tmpList = new ArrayList<>();
        while (!q.isEmpty()) {
                TreeNode node = q.poll();
            tmpList.add(node.val);
            curCount--;
                if (node.left != null) {
                    q.offer(node.left);
                    nextCount++;
                }
                if (node.right != null) {
                    q.offer(node.right);
                    nextCount++;
                }
                if (curCount == 0) {
                    list.add(tmpList);
                    tmpList = new ArrayList<>();
                    curCount = nextCount;
                    nextCount = 0;
                }
        }
        return list;
    }
    
}