自己创建一个h头指针，不存东西，h->next是第一个元素，这样做方便获取链表和插入第一个元素，指针数组按次序存储对应节点的指针

#include<cstdio>
#include<vector>
using namespace std;
struct List{
    int val;
    List *ne;
    List(int x = 0, List* next = nullptr): val(x), ne(next){}
};
int main(){
    int m;
    List* h = new List;
    scanf("%d", &m);
    vector<List*> inptr(m + 1);
    int idx = 0;
    char c;
    getchar();
    while(m--){
        c = getchar();
        int k, x;
        if(c == 'H'){
            scanf("%d", &x);
            inptr[idx] = new List(x, h->ne);
            h->ne = inptr[idx++];
        }
        else if(c == 'D'){
            scanf("%d", &k);
            if(k == 0)
                h->ne = h->ne->ne;
            else if(inptr[k - 1]->ne)
                inptr[k - 1]->ne = inptr[k - 1]->ne->ne;
        }
        else if(c == 'I'){
            scanf("%d%d", &k, &x);
            inptr[idx] = new List(x, nullptr);
            inptr[idx]->ne = inptr[k - 1]->ne;
            inptr[k - 1]->ne = inptr[idx++];
        }
        getchar();
    }
    List *p = h->ne;
    while(p){
        printf("%d ", p->val);
        p = p->ne;
    }
    return 0;
}