二叉排序树

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

typedef struct _tree tree;
struct _tree
{
    char data;
    tree *lchild,*rchild;
    tree *father;
};


typedef struct _tree
{
    char data;
    struct _tree *lchild,*rchild;
    struct _tree *father;
}tree;

tree *Creat(tree *root,char p)
{
    if(root==NULL)
    {
        root=(tree *)malloc(sizeof(tree));
        root->lchild=NULL;
        root->rchild=NULL;
        root->father=NULL;
        root->data = p;
    }
    else
    {
        if(root->data>=p)
        {
            root->lchild=Creat(root->lchild,p);
            root->father = root->lchild;
        }
        else
        {
            root->rchild=Creat(root->rchild,p);
            root->father = root->rchild;
        }
    }
    return root;
}

void PreOrderTraverse(tree *root)
{
    if(root!=NULL)
    {
        PreOrderTraverse(root->lchild);
        printf("%c ", root->data);
        PreOrderTraverse(root->rchild);
    }
}

void InOrderTraverse(tree *root)
{
    if ( root != NULL )
    {
        printf("%c ", root->data);
        InOrderTraverse(root->lchild);
        InOrderTraverse(root->rchild);
    }
}

void PostOrderTraverse(tree *root)
{
    if ( root != NULL )
    {
        PostOrderTraverse(root->lchild);
        PostOrderTraverse(root->rchild);
        printf("%c ", root->data);
    }
}

int main()
{
    tree *root=NULL;
    char p;
    while( p = getchar() )
    {
        if ( p == ' ' || p == '\n' ) continue;
        if ( p == '#' ) break;
        root=Creat(root,p);
    }
    printf("先序： ");
    InOrderTraverse(root);// 先序
    printf("\n");
    printf("中序： ");
    PreOrderTraverse(root); // 中序
    printf("\n后序： ");
    PostOrderTraverse(root);// 后序
    return 0;
}