直接给出代码

#include <iostream>
using namespace std;

const int N = 100005;
int head=-1, idx, e[N], ne[N];

void insertHead(int x) {
    e[idx]=x, ne[idx]=head, head=idx++;
}

void insertK(int x, int k) {
    e[idx]=x, ne[idx]=ne[k], ne[k]=idx++;
}

void delK(int k) {
    ne[k]=ne[ne[k]];
}

int main() {
    char c;
    int m, oper_one, oper_two;
    cin >> m;
    while (m--) {
        cin >> c;
        if (c == 'H') {
            cin >> oper_one;
            insertHead(oper_one);
        }
        else if (c == 'D') {
            cin >> oper_two;
            if (!oper_two) head=ne[head];
            delK(oper_two-1);
        }
        else if (c == 'I') {
            cin >> oper_two >> oper_one;
            insertK(oper_one, oper_two-1);
        }
    }

    for (int index=head; index!=-1; index=ne[index]) cout << e[index] << " ";

    return 0;
}