二叉树构造

BiTNode* CreateBT1(char* pre, char* in, int n)
{
	BiTNode* s;
	char* p;
	int k;
	if (n <= 0)return NULL;
	s = (BiTNode*)malloc(sizeof(BiTNode));
	s->data = *pre;
	for (p = in; p < in + n; p++)
	{
		if (*p == *pre)
			break;
	}
	k = p - in;
	s->lchild = CreateBT1(pre + 1, in, k);
	s->rchild = CreateBT1(pre + k + 1, p + 1, n - k - 1);
	return s;
}

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