结束换行时得用'\0',用'\n'运行通不过，但是在自己的编辑器上是可以的.

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

struct node {
	char val;
	struct node* left;
	struct node* right;
};
int i = 0;
struct node* create(char s[], struct node* mt) {

	if (s[i] != '\0') {
		if (s[i] == '#') {
			i++;
			return NULL;
		}
		mt = (struct node*)malloc(sizeof(struct node));
		mt->val = s[i++];
		mt->left = create(s, mt->left);
		mt->right = create(s, mt->right);
	}
	return mt;
}
void show(struct node* mt) {
	if (mt != NULL) {
		show(mt->left);
		printf("%c ", mt->val);
		show(mt->right);
	}
}
int main() {
	char s[100];
	struct node* mt = NULL;
	while (scanf("%s", s) != EOF) {

		if (s[0] == '0')
			break;
		i=0;//这条语句很关键，每次都得使i=0才可
		mt = create(s, mt);
		show(mt);
		printf("\n");
	}
	return 0;
}