p74e8

#include <iostream>
#include <fstream>

using namespace std;

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

template <class Item>
class DoubleLinkedList
{
    struct Element
    {
        Item inf;
        Element *next;
        Element *prev;
        Element (Item x): inf(x), next(0), prev(0)
        {
        }
    };
    Element *head;
    Element *tail;
    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;
                }
            return cur;
        }
    }
public:
    DoubleLinkedList():head(0), tail(0), size(0) {}

    ~DoubleLinkedList()
    {
        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 InsertHead(Item data, int index)
    {
        if (index < 0 || index > size)
        {
            cout << "Bug";
        }
        else
        {
            Element *newPtr = new Element(data);
            size = GetLength() + 1;
            Element *cur = Find(index-1);
            if (cur == NULL)
            {
                head = newPtr;
                tail = newPtr;
            }
            else
            {
                newPtr->next = cur;
                newPtr->prev = cur->prev;
                cur->prev = newPtr;
                if(cur == head)
                    head = newPtr;
                else newPtr->prev->next = newPtr;
            }
        }
    }
    void InsertTail(Item data, int index)
    {
        if ((index < 0 && head != NULL) || (index > size))
        {
            cout << "Bug";
        }
        else
        {
            Element *newPtr = new Element(data);
            size = GetLength() + 1;
            Element *cur = Find(index-1);
            if (cur == NULL)
            {
                head = newPtr;
                tail = newPtr;
            }
            else
            {
                newPtr->next = cur->next;
                newPtr->prev = cur;
                cur->next = newPtr;
                if(cur == tail)
                {
                    tail = newPtr;
                }
                else
                    newPtr->next->prev = newPtr;
            }
        }
    }
    void Remove (int index)
    {
        if (index < 0 || index > size)
        {
            cout << "Error";
        }
        else
        {
            Element *cur = Find(index);
            size--;
            if (size == 0)
            {
                head = NULL;
                tail = NULL;
            }
            else if (cur == head)
            {
                head = head->next;
                head->prev = NULL;
            }
            else if (cur == tail)
            {
                tail = tail->prev;
                tail->next = NULL;
            }
            else
            {
                cur->prev->next = cur->next;
                cur->next->prev = cur->prev;
            }
            cur->next = NULL;
            cur->prev = NULL;
            delete cur;
        }
    }

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

};

int main (void)
{
    DoubleLinkedList <int> l;
    int i;

    while (in >> i)
        {
            l.InsertTail(i, l.GetLength());
        }

    int k = l.GetLength();
    for (int i = 0; i < k; i++)
    {
        if (l.Get(i) % 2 == 0)
        {
            l.InsertTail(l.Get(i), i);
            k++;
            i++;
        }
    }

    l.Print(out);
}