算法.单链表

#include<iostream>
using namespace std;
const int N = 100010;
int e[N], en[N], p,head=-1;
void headinsert(int x)
{
    e[p] = x, en[p] = head, head = p++;
}
void insert(int k,int x)
{
    e[p] = x, en[p] = en[k], en[k] = p++;
}
void del(int k)
{
    en[k] = en[en[k]];
}

int main()
{
    char a;
    int n,k,x;
    cin >> n ;
    
    while (n--)
    {
        cin >> a ;
        if (a == 'D')
        {
            cin >> k;
            if (!k)head = en[head];
            else del(k-1);
        }
        else if (a == 'I')
        {
            cin >> k;
            cin >> x;
            insert(k-1, x);
        }
        else
        {
            cin >> x;
            headinsert(x);
        }
    }
    for (int i = head; i != -1; i = en[i])
    {
        cout << e[i]<<" ";
    }
    


    return 0;
}