#include<stdio.h>
#include<stdlib.h>
typedef char ElemType;
//结点定义
typedef struct node{
    ElemType data;
    struct node* lchild,*rchild;
}BiTNode,*BiTree;

//初始化一个空的二叉树
void InitBiTree(BiTree &tree)
{
    // tree存储NULL,表示没有二叉树
    tree=NULL;
}
//创建二叉树  #表示空结点
void CreateBitree(BiTree &T)
{
    char ch;
    if((ch=getchar())=='#')
        T=NULL;
    else
    {
        T=(BiTNode*)malloc(sizeof(BiTNode));
        T->data=ch;
        CreateBitree(T->lchild);
        CreateBitree(T->rchild);
    }
}
//先序遍历二叉树
void preOrder(BiTree &tree)
{
    if(tree!=NULL)
    {
        printf("%c",tree->data);
        preOrder(tree->lchild);
        preOrder(tree->rchild);
    }
}
//中序遍历二叉树
void InOrder(BiTree &tree)
{
    if(tree!=NULL)
    {
        InOrder(tree->lchild);    //一直访问到最左边的叶子节点
        printf("%c",tree->data);
        InOrder(tree->rchild);
    }
}
//后序遍历
void PostOrder(BiTree &tree)
{
    if (tree!=NULL)
    {
        PostOrder(tree->lchild);
        PostOrder(tree->rchild);
        printf("%c",tree->data);
    }
}
int main()
{
    BiTree tree;
    InitBiTree(tree);
    CreateBitree(tree);
    printf("先序遍历:");
    preOrder(tree);
    printf("\n");
    printf("中序遍历:");
    InOrder(tree);
    printf("\n");
    printf("后序遍历:");
    PostOrder(tree);
    return 0;
}