Rt，以下程序为什么会有问题（输入完 $n$ 后再输入一个数就会炸）

struct NodeList
{
	int val;
	NodeList *pre,*nxt;
	NodeList(){pre = nxt = nullptr,val = 0;}
} *List[_];

int n;
int cnt;

int main()
{
	NodeList* LastBlock = List[0];
	cin >> n;
	for(int i = 1;i <= n;i++)
	{
		int k;
		cin >> k;
		NodeList* New = new NodeList;
		New -> val = k;
		New -> pre = LastBlock;
		LastBlock -> nxt = New;
		LastBlock = LastBlock -> nxt;
	}
//	for(NodeList* i = List[0] -> nxt;i -> nxt != nullptr;i = i->nxt)
//		cout << i->val << " ";
	return 0;
}