LinkedList.h

#include<iostream>

using namespace std;

class LinkedList
{
    static struct node
    {
        int x;
        node* next;
        node* prev;
    };
    node* start;
    node* end;
    int size;
    node* _sort(node* r, int n);
    static void _swap(node* a, node* b){
        int t = a->x;
        a->x = b->x;
        b->x = t;
    }

public:

    LinkedList();
    ~LinkedList();

    friend ostream& operator<<(ostream& out, const LinkedList& l);

    int push(int x);
    int pop();
    int unshift(int x);
    int shift();

    int find(int x);
    LinkedList* copy(int s, int e);
    LinkedList* splice(int s, int e);

    void sort(){
        start = _sort(start, size);
    }
};