题解 | #把二叉树打印成多行#

import java.util.Queue;
import java.util.ArrayList;
import java.util.*;

/*
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 pRoot) {
        ArrayList<ArrayList<Integer>> res = new ArrayList<>();
        if(pRoot == null) return res;
        Queue<TreeNode> q = new LinkedList<>();
        q.offer(pRoot);
        while(!q.isEmpty()) {
            int sz = q.size();
            ArrayList<Integer> temp = new ArrayList<>();
            for(int i = 0; i < sz; i++) {
                TreeNode node = q.poll();
                temp.add(node.val);
                if(node.left != null) q.offer(node.left);
                if(node.right != null) q.offer(node.right); 
            }
            res.add(temp);
        }
        return res;
    }
    
}