顺序存储二叉树

package jiegou.tree;

import jdk.packager.services.userjvmoptions.PreferencesUserJvmOptions;

import java.util.ArrayList;

public class ArrayTreeDemo {
    public static void main(String[] args) {
        int[] arr = {1,2,3,4,5,6,7};

        ArrayBinaryTree arrayBinaryTree = new ArrayBinaryTree(arr);
        arrayBinaryTree.preOrder();
    }
}

class ArrayBinaryTree
{
    private int[] arr;// 存储数组

    public ArrayBinaryTree(int[] arr)
    {
        this.arr = arr;
    }

    public void preOrder(){
        this.preOrder(0);
    }

    // 完成顺序存储
    // index 数组的下标
    public void preOrder(int index)
    {
        if(arr == null || arr.length == 0) {
            System.out.println("数数为空 不能按二叉树遍历");
            return;
        }

        // 根
        System.out.println(arr[index]);

        // 左
        if(index * 2 +1 < arr.length ){
            preOrder(index*2+1);
        }

        // 右
        if(index * 2 +2 < arr.length){
            preOrder(index*2 + 2);
        }
    }
}