p75e17

#include <iostream>
#include <fstream>
using namespace std;

ifstream in("input.txt");
ofstream out("output.txt");

template <class Item>
class List
{
    struct Element
    {
        Item inf;
        Element *next;
        Element (Item x): inf(x), next(0)
        {
        }
    };
    Element *head;
    int size;
    Element *Find(int index)
    {
        if(index < 0 || index > size)
            return NULL;
        else
        {
            Element *cur = head;
             int i = 0;
             while (i < index)
             {
                 if (cur->next == NULL) break;
                 i++;
                 cur = cur->next;
             }
            /*for(int i = 0; i < index; i++)
                if (cur != NULL)
                    cur = cur->next;
                else break;*/
            return cur;
        }
    }
public:
    List():head(0), size(0)
    {
    }
    ~List()
    {
        while(!Empty())
            Remove(0);
    }
    bool Empty()
    {
        return head == 0;
    }
    int GetLength()
    {
        return size;
    }
    Item Get(int index)
    {
        if (index < 0 || index > size)
        {
            cout << "Error";
        }
        else
        {
            Element *r = Find(index);
            Item i = r->inf;
            return i;
        }
        return 0;
    }
    void Insert(Item data, int index)
    {
        if (index < 0 || index > size)
        {
            cout << "Bug";
        }
        else
        {
            Element *newPtr = new Element(data);
            size = GetLength() + 1;
            if (index == 0)
            {
                newPtr->next = head;
                head = newPtr;
            }
            else
            {
                Element *prev = Find(index-1);
                newPtr->next = prev->next;
                prev->next = newPtr;
            }
        }
    }
    void Remove (int index)
    {
        if (index < 0 || index > size)
        {
            cout << "ERROR at " << index << endl;
        }
        else
        {
            Element *cur;
            size--;
            if (index == 0)
            {
                cur = head;
                head = head->next;
            }
            else
            {
                Element * prev = Find(index-1);
                cur = prev->next;
                prev->next = cur->next;
            }
            cur->next = NULL;
            delete cur;
        }
    }

    void Print(ofstream &out)
    {
        for(Element * cur = head; cur != NULL; cur = cur->next)
            out << cur->inf << " ";
        out << endl;
    }
};

int main(void)
{
    List <int> l;
    List <int> res;
    int i;
    while (in >> i)
        {
            l.Insert(i, l.GetLength());
        }

   int k = l.GetLength();
    for (int i = 0; i < k; i++)
    {
        if (l.Get(i) < 0)
            {
                res.Insert(l.Get(i),  res.GetLength());
                l.Remove(i);
                i--;
                k--;
            }
    }

    for (int i = 0; i < k; i++)
    {
        res.Insert(l.Get(i),res.GetLength());
        l.Remove(i);
        i--;
        k--;
    }
    res.Print(out);
}