数据结构 树的建立与遍历

#include<stdio.h>
#include<stdlib.h>

typedef char ElemType;

typedef struct node{
    ElemType data;
    struct node *lson;
    struct node *rson;
}Bynode,*Bytree;

Bytree CreateBytree()//树的建立
{
    char ch;
    Bytree t;
    ch = getchar(); 
    if ( ch == '1')
        t = NULL;
    else 
    { 
        t = (Bytree)malloc(sizeof(Bynode));
        t->data = ch;
        t->lson = CreateBytree();
        t->rson = CreateBytree();
     }
    return t;
}

void pre(Bytree t)//先序遍历
{
    if(t)
    {
        putchar(t->data);
        pre(t->lson);
        pre(t->rson);
    }
}

void in(Bytree t)//中序遍历
{
    if(t)
    {
        in(t->lson);
        putchar(t->data);
        in(t->rson);
    }
}

void post(Bytree t)//后序遍历
{
    if(t)
    {
        post(t->lson);
        post(t->rson);
        putchar(t->data);
    }
}

void main()
{
    Bytree t;
    t=CreateBytree();
    printf("先序遍历：");
    pre(t);
    putchar('\n');
    printf("中序遍历：");
    in(t);
    putchar('\n');
    printf("后续遍历：");
    post(t);
    putchar('\n');
}