[编程题]把二叉树打印成多行

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
/*
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) {
        //记录层数
        int layer=1;
        ArrayList<ArrayList<Integer>> result=new ArrayList<ArrayList<Integer>>();
        if(pRoot==null){
            return result;
        }
        //存放奇数层的节点s
        Queue<TreeNode> s1= new LinkedList<TreeNode>();
        s1.offer(pRoot);
        //存放偶数层节点
        Queue<TreeNode> s2= new LinkedList<TreeNode>();
        while(!s1.isEmpty()||!s2.isEmpty()){
            //奇数层
            if(layer%2!=0){
                ArrayList<Integer> result1=new ArrayList<Integer>();
                while(!s1.isEmpty()){
                TreeNode curNode=s1.poll();
                if(curNode!=null){
                    result1.add(curNode.val);
                    s2.offer(curNode.left);
                    s2.offer(curNode.right);
                }
                }
                if(!result1.isEmpty()){
                    result.add(result1);
                    layer++;
                }
            }else{
                //偶数层
                ArrayList<Integer> result2=new ArrayList<Integer>();
                while(!s2.isEmpty()){
                    TreeNode curNode=s2.poll();
                    if(curNode!=null){
                        result2.add(curNode.val);
                        s1.offer(curNode.left);
                        s1.offer(curNode.right);
                    }
                }
                if(!result2.isEmpty()){
                    result.add(result2);
                    layer++;
                }
            }
        }
        return result;
    }

}