DS作业·写了一个链表

#include<iostream>
#include <string>
#include<list>
#include<fstream>
using namespace std;
list<int> l;
typedef long long ll, rr;
const int H = 1e9;
struct mlist  {
    int d;
     mlist *prior;
    mlist *next;
    mlist(int d=0, mlist* prior = NULL, mlist*  next = NULL) :d(d), prior(prior), next(next) {}//指向自己。
    mlist * setpos(int i) {
        mlist *p = next;
        int count = 1;
        if (i < 0) {
            cout << "illegal find" << endl; return NULL;
        }
        while (p != NULL&&count<i) {
            p = p->next;
            count++;
        }
        return p;
    }
    mlist* rbegin() {
        mlist *p = next;
        while (p != NULL)p = p->next;
        return  p;
    }
    void pb(int x) {//find this list‘s end,attach to it;
        if (next == NULL) {
            mlist *now=new mlist(x, next, NULL);
            next = now;
            return;
        } 
        mlist *p = next;
         while (p->next != NULL)p = p->next;
        mlist *now;
        now = new mlist(x, p, NULL);
        p->next = now;
        
    }
    void pf(int x) {//find this list‘s end,attach to it;
        if (next == NULL) {
            mlist *now = new mlist(x, next, NULL);
            next = now;
            return;
        }
        
        
        mlist *now;
        now = new mlist(x, next->prior, next);
        next = now;

    }
    bool insert(int i, int x) {//第i个后面插入x，i从1开始
        if (i == 0) pf(x);
        else  {
            mlist *p = next, *q;
            if ((p =setpos(i )) == NULL) {//前1个
                cout << "illegal insertion" << endl;
                return false;
            }
            q = new mlist(x, p->prior, p->next);
            p->next = q;
            return true;
        }
    }
    bool erase(int i) {//第i个后面插入x，i从1开始

        if (i == 1) {
            mlist*q = next;
            
            next = next->next;
            delete q;
        }
        else {
            mlist *p = next, *q;
            if ((p = setpos(i - 1)) == NULL) {//第i个
                cout << "illegal deletion" << endl;
                return false;
            }
            q = p->next;
            p->next = p->next->next;
            delete (q);
            return true;
        }
    }
    int size() {
        int cnt = 0;
        mlist* p = next;
        while (p != NULL) {
            p = p->next;
            cnt++;
        }
        return cnt;
    }
    void reverse() {
        int n = size();
        int t = n;
        for(int i=1;i<=n;i++) {
            int x = setpos(n)->d;
            erase(n);
            insert(i-1, x);
            
        }
    
            

        
    }
};
mlist init() {
    mlist x;
    x.d = H;
    x.next = x.prior = NULL;
    return x;
}
 void homework1() {
     ifstream fin("1.txt");
     int n; fin >> n;
     for (int i = 1; i <= n; i++) { int x; fin >> x; l.push_back(x); }
     auto e = l.end();
     for (auto t = l.begin(); t != e; t++) {
         if (*t < 0)l.push_front(*t);
         else l.push_back(*t);
         t = l.erase(t);
     }
     for (auto t : l) { cout << t << ‘ ‘; }
 }
 mlist head = init();
 void print(mlist head) {
     mlist *p = &head;
     while (p != NULL) cout << p->d << ‘ ‘, p = p->next;
     cout << endl;
 }
int main() {
    
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)head.pb(i);
    print(head);
    head.reverse();
    print(head);
    //cout << head.size();
     cin >> n;
}
/*p->prior->next = p->next;
p->next->prior = p->prioir;
free(p);*/

/*template<class T> class Link {//const
public:
    T data;
    Link<T> *next;
    Link(const T info, const Link<T>*nextValue = NULL) {
        data = info;
        next = nextValue;
    }
    Link(const Link<T>*nextValue) {
        next = nextValue;
    }
};
template<class T> class InkList :public List<T> {
private:
    Link<T> *head, *tail;
    Link<T> *setPos(const int p);
public:
    ~InkList(int s);
    //ADT 
    bool isEmpty();
    void clear();
    int length();
    bool append(const T value);
    bool insert(const int p, const T value);
    bool delete1(const int p);
    bool getValue(const int p, T& value);
    bool getPos(int &p, const T value);
};
//第i个的指针  
template<class T>
Link<T> *InkList<T>::setPos(int i) {
    int count = 0;
    if (i == -1)
        return head;
    link<T>*p = head->next;
    while (p != NULL&&count < i) {
        p = p->next;
        count++;
    }; 
    return p;
}
//insert  tail??new??
template<class T>
bool InkList<T>::insert(const int i, const T value) {
    Link<T> *p*q;

    if ((p = setPos(i - 1)) == NULL) {
        cout << "illegal insertion" << endl;
        return false;
    }
    q = new Link<T>(value, p->next);
    p->next = q;
    if (p == tail)
        tail = q;
    return true;
}
//delete
template<class T>
bool InkList<T>::delete1(const int i) {//delete 内置函数
    Link<T>*q, *p;
    if ((p = setPos(i - 1)) == NULL || p == tail) {
        cout << "illegal deletion" << endl;
        return false;
    }
    q = p->next;
    if (q == tail) {
        tail = p;
        p->next = NULL;
    }
    else p->next = q->next;
    delete q;
    return true;
}
    /*p = head;//delete by x;
while (p->next != NULL&&p->next->info != x) p = p->next;
q = p->next;
p->next = q->next;
free(q);*/