题解 | #把二叉树打印成多行#

import java.util.*;
public class Solution {
    ArrayList<ArrayList<Integer> > Print(TreeNode pRoot) {
        ArrayList<ArrayList<Integer> > res = new ArrayList<>();
        if(pRoot == null) return res;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(pRoot);
        while(!queue.isEmpty()) {
            int size = queue.size();
            ArrayList<Integer> list = new ArrayList<>();
            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;
    }

}