#include<bits/stdc++.h> using namespace std; typedef struct Node * ptrtonode; typedef struct Node { int data,order; ptrtonode next; } node; int main() { ptrtonode head=new node(); head->next=NULL; int n,a,b; char c; scanf("%d",&n); int o=1; for(int i=1; i<=n; i++) { ptrtonode q; ptrtonode p; cin>>c; if(c=='H') { p=new node(); scanf("%d",&a); p->data=a; p->order=o; o++; p->next=head->next; head->next=p; } else if(c=='D') { cin>>a; if(a==0) { p=head->next; head->next=p->next; free(p); } else { q=head->next; while(q->order!=o) { q=q->next; } p=q->next; q->next=p->next; } } else if(c=='I') { scanf("%d%d",&a,&b); p=head->next; while(p->order!=a) { p=p->next; } q=new node(); q->data=b; q->order=o; o++; q->next=p->next; p->next=q; } } head=head->next; while(head) { cout<<head->data<<" "<<head->order<<endl; head=head->next; } return 0; }哪里有错误

这段代码的错误是使用了 `free()` 函数，而 `free()` 函数是 C 语言的函数，在 C++ 中应该使用 `delete` 或 `delete[]` 来释放内存。另外，使用 `cin` 读入字符时应该加上 `#include <iostream>`。下面是修改过的代码：

#include<iostream>
using namespace std;

typedef struct Node * ptrtonode;
typedef struct Node {
    int data, order;
    ptrtonode next;
} node;

int main() {
    ptrtonode head = new node();
    head->next = NULL;
    int n, a, b;
    char c;
    cin >> n;
    int o = 1;
    for(int i = 1; i <= n; i++) {
        ptrtonode q;
        ptrtonode p;
        cin >> c;
        if(c == 'H') {
            p = new node();
            cin >> a;
            p->data = a;
            p->order = o;
            o++;
            p->next = head->next;
            head->next = p;
        }
        else if(c == 'D') {
            cin >> a;
            if(a == 0) {
                p = head->next;
                head->next = p->next;
                delete p;
            }
            else {
                q = head->next;
                while(q->order != o) {
                    q = q->next;
                }
                p = q->next;
                q->next = p->next;
                delete p;
            }
        }
        else if(c == 'I') {
            cin >> a >> b;
            p = head->next;
            while(p->order != a) {
                p = p->next;
            }
            q = new node();
            q->data = b;
            q->order = o;
            o++;
            q->next = p->next;
            p->next = q;
        }
    }
    head = head->next;
    while(head) {
        cout << head->data << " " << head->order << endl;
        head = head->next;
    }
    return 0;
}