图的建立及输出其先序序列，中序序列，后续序列

#include<stdio.h>
#include<malloc.h>
typedef struct node{
    char data;
    struct node *left;
    struct node *right;
}Node;

int i = 0;
char str[100];

void create(Node** p){
    if(str[i] == '')
        return ;
    if(str[i++] != '#'){
        *p = (Node*)malloc(sizeof(Node));
        (*p)->left = (*p)->right = NULL;
        (*p)->data = str[i-1];
        create(&(*p)->left);
        create(&(*p)->right);
    }
}

void print(Node *p){
    if(p != NULL && p->data != '#'){
        printf("%c ",p->data);
        print(p->left);
        print(p->right);
    }
}

void print_2(Node *p){
    if(p != NULL && p->data != '#'){
        print_2(p->left);
        printf("%c ",p->data);
        print_2(p->right);
    }
}

void print_3(Node *p){
    if(p != NULL && p->data != '#'){
        print_3(p->left);
        print_3(p->right);
        printf("%c ",p->data);
    }
}

int main(){
    gets(str);
    Node *head = NULL;
    create(&head);
    printf("先序序列：");
    print(head);
    printf("
中序序列：");
    print_2(head);

    printf("
后序序列：");
    print_3(head);

    return 0;
}