先序顺序输入结点值创建二叉树，并按先序，中序和后序遍历输出

将如图所示的二叉树通过先序的顺序输入根据其值创建二叉树，如果某个节点其左子树为空，则用 * 代替其左子树节点值，如果某个节点其右子树为空，则用 * 代替其右子树节点值，按照此方式一次性输入节点值用空格隔开就可以得到先序，中序，后序遍历输出

Copyright vivi_and_qiao liwei
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 先序顺序输入结点值创建二叉树_并按先序_中序和后序遍历输出
{
public struct value
   {
public static string inputStr;
public static string[] valueStr;
public static int i = 0;
   }
public class tree
    {
public string data { get; set; }
public tree lchild { get; set; }
public tree rchild { get; set; }
    }
public static class Operation
    {
public static void Create(tree t)
        {
string temp = value.valueStr[value.i++];
//Console.WriteLine("读取了字符" + temp);
if (temp == '*'.ToString())
            {
                t.lchild = null ;
                t.rchild = null;
            }
else
            {
                t.data = temp;
                tree lchild=new tree();
                tree rchild = new tree();
                t.lchild = lchild;
                t.rchild = rchild;
                Operation.Create(t.lchild);
                Operation.Create(t.rchild);
            }
        }
public static void preorder_traversal(tree t)
        {
if (t == null)
return;
else
            {
if (t.data != null)
                Console.Write(t.data+" ");
                preorder_traversal(t.lchild);
                preorder_traversal(t.rchild);
            }
        }
public static void inorder_traversal(tree t)
        {
if (t == null)
return;
else
            {
                inorder_traversal(t.lchild);
if(t.data!=null)
                Console.Write(t.data+" ");
               inorder_traversal(t.rchild);
            }
        }
public static void postorder_traversal(tree t)
        {
if (t == null)
return;
else
            {
            postorder_traversal(t.lchild);
            postorder_traversal(t.rchild);
if (t.data != null)
            Console.Write(t.data+" ");
             }
        }
    }
    class Program
    {
static void Main(string[] args)
        {
value.inputStr = Console.ReadLine();
value.valueStr = value.inputStr.Split(' '); 
            tree t = new tree();
            Operation.Create(t);
            Console.WriteLine("先序遍历：");
            Operation.preorder_traversal(t);
            Console.WriteLine('\n'+"中序遍历：");
            Operation.inorder_traversal(t);
            Console.WriteLine('\n'+"后序遍历：");
            Operation.postorder_traversal(t);
            Console.ReadKey();
        }
    }
}