采用先序遍历 和层次遍历递归建立二叉树--进行封装

package com.offer;

public class TreeNode {
    
int val = 0;
TreeNode left = null;
TreeNode right = null;

public TreeNode(int val)
{
    this.val=val;
}

public TreeNode()
{
    CreateBinaryTree();// 采用默认的
    //preShow(this.root);
}
public TreeNode(int array[])
{
   this.root=CreateBinaryTree(array);
}
public TreeNode root;  

public void CreateBinaryTree()
{
    int array[]={5,3,6,-1,-1,2,-1,-1,1,-1,-1};
    this.root=CreateBinaryTree(array);
}
public TreeNode CreateBinaryTree(int array[])
{
    
    /**第一种建立二叉树方式采用先序遍历建立二叉树**/
    return CreateTreePre(array);
    
    /**第二种方式采用层次遍历方式建立二叉树*/
    //return CreteTreeLevel(array,0);
}

@SuppressWarnings("unused")
private TreeNode CreateTreeLevel(int[] array,int index) {
    if(index>=array.length || array[index]==-1)
        return null;
    TreeNode node=new TreeNode(array[index]);
    node.left=CreateTreeLevel(array,2*index+1);
    node.right=CreateTreeLevel(array,2*(index+1));
    return node;
}
private int index=0;

private TreeNode CreateTreePre(int array[])
{
      int val=array[index++];
      if(val==-1)
            return null;
        else
        {
            TreeNode node=new TreeNode(val);
            node.left=CreateTreePre(array);
            node.right=CreateTreePre(array);
            return node;
        }
}
       
public void preShow(TreeNode node) { // 先序遍历  
    if (node != null) {  
        System.out.print(node.val + " ");  
        preShow(node.left);  
        preShow(node.right);  
    }  
}  

 public static void main(String[] args)
 {
    TreeNode r=new TreeNode();}
}