import java.util.ArrayList;import java.util.Collections;import java.util.LinkedList;import java.util.Queue;/** * 面试题61：按之字形顺序打印二叉树 * 请实现一个函数按照之字形打印二叉树，即第一行按照从左到右的顺序打印，第二层按照从右至左的顺序打印，第三行按照从左到右的顺序打印，其他行以此类推。 */public class _61_font {    public static void main(String[] args) {        TreeNode61 treeNode61 = new TreeNode61(1);        treeNode61.left= new TreeNode61(2);        treeNode61.right= new TreeNode61(3);        treeNode61.left.left= new TreeNode61(4);                Solution61 solution61 = new Solution61();        ArrayList
    
     
      > print = solution61.Print(treeNode61);        for(ArrayList
      
        a:print){            for(Integer b:a){                System.out.print(b+"、");            }            System.out.println();        }    }}class Solution61 {    public ArrayList
       
        
         > Print(TreeNode61 pRoot) {        ArrayList
         
          
           > arrayList = new ArrayList
           
            
             >(); if (pRoot == null) { return arrayList; } Queue
             
               queue=new LinkedList
              
               (); ArrayList
               
                 row=new ArrayList
                
                 (); queue.add(pRoot); boolean flag=false; while(!queue.isEmpty()){ row=new ArrayList
                 
                  (); //每次重新生成一个对象 int len=queue.size(); row.clear(); for(int i=0;i