Binary tree structure and threaded binary

In sequence preorder configured

BTNode* CreateBT(char* pre, char* in, int n)
{
	char* p;
	BTNode* b;
	int k;
	if (n <= 0)
		return NULL;
	b = (BTNode*)malloc(sizeof(BTNode));
	b->data = *pre;
	for (p = in; p < in + n; p++)
	{
		if (*p == *pre)
			break;
	}
	k = p - in;
	b->lchild = CreateBT(pre+1, in, k);
	b->rchild = CreateBT(pre + k + 1, p+1, n - k - 1);
	return b;
}

　　After the configuration Sequence Number

BTNode* CreateBT2(char* in, char* post, int n)
{
	int k;
	char* p;
	BTNode* b = (BTNode*)malloc(sizeof(BTNode));
	if (n <= 0)
		return NULL;
	b->data = *(post + n - 1);
	for (p = in; p < in + n; p++)
	{
		if (*p == *(post + n - 1))
			break;
	}
	k = p - in;
	b->lchild = CreateBT2(in, post, k);
	b->rchild = CreateBT2(p + 1, post + k, n - k - 1);
	return b;
}