典型的利用指针加减模拟删除和增加文档

#include<bits/stdc++.h>
using namespace std;
int top=1;
bool a[100010];
int main()
{
    int n;
    cin>>n;
    string s;
    int id;
    for(int i=1;i<=n;i++)
    {
        cin>>s;
        if(s=="New")
        {
            a[top]=true;
            cout<<top<<endl;
            while(a[top]==true)
            {
                top++;
            }
        }
        else
        {
            cin>>id;
            if(a[id]==true)
            {
                cout<<"Successful"<<endl;
                a[id]=false;
                if(id<top)top=id;
            }
            else cout<<"Failed"<<endl;
        }
    }
    return 0;
}