面试题 32(2)：之字形打印二叉树

 

 

import java.util.ArrayList;
import java.util.Stack;
/**
 * 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 ZhiZiXingDaYinErChaShu {
    public static void main(String[] args) {
        TreeNode15 node15 = new TreeNode15(8);
        node15.left = new TreeNode15(6);
        node15.right = new TreeNode15(10);
        Solution15 solution15 = new Solution15();
        ArrayList<ArrayList<Integer>> resultList = solution15.Print(node15);
        for(ArrayList<Integer> list : resultList){
            for(Integer num : list){
                System.out.print(num+",");
            }
            System.out.println();
        }
    }
}



class TreeNode15 {
    int val = 0;
    TreeNode15 left = null;
    TreeNode15 right = null;

    public TreeNode15(int val) {
        this.val = val;

    }
}

class Solution15{
    public ArrayList<ArrayList<Integer>> Print(TreeNode15 pRoot) {
        ArrayList<ArrayList<Integer>> listAll = new ArrayList<ArrayList<Integer>>();
        if(pRoot == null)
            return listAll;
        Stack<TreeNode15>[] stacks = new Stack[2];
        stacks[0]=new Stack<TreeNode15>();
        stacks[1]=new Stack<TreeNode15>();
        int current=0,next=1;
        stacks[0].push(pRoot);
        ArrayList<Integer> list = new ArrayList<Integer>();
        while(stacks[0].size()!=0 || stacks[1].size()!=0){
            TreeNode15 treeNode15 = stacks[current].pop();
            list.add(treeNode15.val);
            if(current==0){
                if(treeNode15.left!=null){
                    stacks[next].push(treeNode15.left);
                }
                if(treeNode15.right!=null){
                    stacks[next].push(treeNode15.right);
                }
            }else{
                if(treeNode15.right!=null){
                    stacks[next].push(treeNode15.right);
                }
                if(treeNode15.left!=null){
                    stacks[next].push(treeNode15.left);
                }
            }
            if(stacks[current].size()==0){
                listAll.add(list);
                list=new ArrayList<Integer>();
                current=1-current;
                next=1-next;
            }
        }
        return listAll;
    }
}