题解 | #按之字形顺序打印二叉树#

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 {
    public ArrayList<ArrayList<Integer> > Print(TreeNode pRoot) {
        if(pRoot == null){
            return new ArrayList<>();
        }
        ArrayList<ArrayList<Integer>> ans = new ArrayList<>();
        
        Queue<TreeNode> queue = new LinkedList<>();
        queue.add(pRoot);
        //记录第几层，从0层开始
        int count =  0;
        while(!queue.isEmpty()){
            LinkedList<Integer> list = new LinkedList<>();
            for(int i = 0;i<size;i++){
                if(count%2==0){
                }else{
                    list.addFirst(cur.val);
                }
                
                if(cur.left!=null)
                    queue.add(cur.left);
                    
                if(cur.right!=null)
                    queue.add(cur.right);
                    
            count++;
            ans.add(new ArrayList<>(list));
            
        }
        return ans;
    }

}