学步园

练习的程序，有错指出。

#include<stdio.h>
#include<malloc.h>
typedef struct node
{
	char a;
	struct node *left;
	struct node *right;
}root;
root *create()
{
	root* p;
	root* s[100];
	int i,j;
	char c;
	printf("i and c=");
	scanf("%d %c",&i,&c);
	while(i!=0&&c!='#')
	{
		p=(root*)malloc(sizeof(root));
		p->a=c;
		p->left=NULL;
		p->right=NULL;
		s[i]=p;
		if(i!=1)
		{
			j=i/2;
			if(i%2==0)
				s[j]->left=p;
			else
				s[j]->right=p;
		}
		printf("i and c=");
		scanf("%d %c",&i,&c);
	}
	return s[1];
}
void inorder(root* t)
{
	if(t)
	{
		inorder(t->left);
		printf("%c ",t->a);
		inorder(t->right);
	}
}
void pre(root* t)
{
	if(t)
	{
		printf("%c ",t->a);
		pre(t->left);
		pre(t->right);
	}
}
void post(root * t)
{
	if(t)
	{
		post(t->left);
		post(t->right);
		printf("%c ",t->a);
	}
}
int main()
{
	int a;
	root* bt;
	bt=create();
	while(1)
	{
		printf("中序遍历请按1，先序遍历请按2，后序遍历请按3：");
		scanf("%d",&a);
		switch(a)
		{
			case 1:
			inorder(bt);
			printf("\n");
			break;
			case 2:
			pre(bt);
			printf("\n");
			break;
			case 3:
			post(bt);
			printf("\n");
			break;
			default:
			break;

			
		}
	}
	return 1;
}