IntDList

//Создать список из целых чисел. Создать новый список, записав в него вначале все четные, а затем все нечетные числа из исходного списка.
#include <iostream>
#include <fstream>
using namespace std;
ifstream in ("input.txt");

struct IntDListNode {
    int value;
    IntDListNode* prev;
    IntDListNode* next;
};

class IntDList {
public:
    IntDListNode* head;
    IntDListNode* tail;
    int size;
    /*void addAtBeg(int value) {
        IntDListNode* node = new IntDListNode;
        node->prev = 0;
        node->value = value;
        node->next = head;
        if(!size) head = tail = node;
        else {
            head->prev = node;
            head = node;
        }
        size++;
    }*/
    void addToEnd(int value) {
        IntDListNode* node = new IntDListNode;
        node->prev = tail;
        node->value = value;
        node->next = 0;
        if(!size) head = tail = node;
        else {
            tail->next = node;
            tail = node;
        }
        size++;
    }
    void toHead(IntDListNode* node) {
        if (node->next) node->next->prev = node->prev;
        if (node->prev) node->prev->next = node->next;

        node->prev = 0;
        node->next = head;
        head->prev = node;
        head = node;
    }
    void output() {
        IntDListNode* node = head;
        //cout << "list size = " << size << endl;
        while (node) {
            cout << node->value << ' ';
            node = node->next;
        }
        cout << endl;
    }
    IntDList(): head(0), tail(0), size(0) {}
};

int main() {
    int n; in >> n;
    IntDList list;
    for (int i = 0; i < n; i++) {
        int v; in >> v;
        list.addToEnd(v);
    }

    IntDListNode* curr = list.head;
    IntDListNode* nxtnode;
    while (curr) {
        nxtnode = curr->next;
        if (!(curr->value % 2)) list.toHead(curr);
        curr = nxtnode;
    }

    /*IntDListNode* curr;
    IntDListNode* srtend = list.head;
    IntDListNode* nxtnode;
    while (!(srtend->value % 2) && srtend) srtend = srtend->next;
    if (srtend) curr = srtend->next;
    while (curr) {
        nxtnode = curr->next;
        if (!(curr->value % 2)) {
            curr->next->prev = curr->prev;
            curr->prev->next = curr->next;

            curr->prev = srtend->prev;
            curr->next = srtend;
            curr->prev->next = curr;
            srtend->prev = curr;
        }
        curr = nxtnode;
    }*/

    list.output();
}