double list

#ifndef LIST_H_
#define LIST_H_

struct Node
{
	int data;
	Node *next;
	Node *pre;
	Node(int d){ data = d; }
};

class List
{
public:
	List();
	List(int *arr, int size);    //根据数组构造链表
	~List();
	Node *getHead(){ return head; }
	void setHead(Node *newHead){ head = newHead; tail = newHead; }
	void display();              //从头显示链表
	void display(int);           //从尾显示链表
	Node *find(const int num);   //寻找元素num,返回对应结点，没找到返回NULL
	void transfer(Node *position, Node *first, Node *last);    //将结点[first,last)之间的元素移动到position节点之前,注意是前开后闭
	void merge(List &list);      //两个递增的链表合并成一个递增的链表
	void reverse();              //反转链表
	void swap(List &list);       //交换链表
	void sort();                 //排序
private:
	Node *head;
	Node *tail;
};

#endif

#include "list.h"
#include <iostream>
using namespace std;
List::List()
{
	head = new Node(0);   //哨兵节点
	tail = head;
	head->next = tail;
	tail->pre = head;
	tail->next = head;
	head->pre = tail;
}

List::List(int *arr, int size)
{
	tail = new Node(0);
	head = tail;
	head->pre = tail;
	tail->next = head;
	if (size == 0) return;
	Node *p = NULL, *f = tail;
	for (int i = 0; i < size; i++)
	{
		Node *temp = new Node(arr[i]);
		if (i == 0)	head->next = temp;
		else
		{
			p->next = temp;
			p->pre = f;
			f = p;
		}
		p = temp;
	}
	p->next = tail;
	p->pre = f;
	tail->pre=p;
}

List::~List()
{
	while (head != tail)
	{
		Node *p = head->next;
		delete head;
		head = p;
	}
	delete head;
}

void List::display()
{
	Node *p = head->next;
	while (p != tail)
	{
		cout << p->data << " ";
		p = p->next;
	}
	cout << endl;
}


void List::display(int)
{
	Node *p = tail->pre;
	while (p != tail)
	{
		cout << p->data << " ";
		p = p->pre;
	}
	cout << endl;
}

Node *List::find(int num)
{
	Node *p = head->next;
	while (p != tail)
	{
		if (p->data == num) return p;
		p = p->next;
	}
	return NULL;
}

void List::transfer(Node *position, Node *first, Node *last)
{
	if (position != last)
	{
		last->pre->next = position;            //(1)
		position->pre->next = first;           //(2)
		first->pre->next = last;               //(3)
		//此处不能这样：first->pre=position->pre;如果这样，first原来的pre就丢了，所以不需有个temp
		Node *temp = position->pre;            //(4)
		position->pre = last->pre;             //(5)
		last->pre = first->pre;                //(6)
		first->pre = temp;                     //(7)
	}
}

void List::merge(List &list)
{
	Node *tail2 = list.getHead();
	Node *p1 = head->next, *p2 = tail2->next;

	while (p1 != tail && p2 != tail2)
	{
		if (p2->data < p1->data)
		{
			Node *n = p2;
			n = n->next;
			transfer(p1, p2, n);
			p2 = n;
		}
		else p1 = p1->next;
	}
	if (p2 != tail2) transfer(p1, p2, tail2);
}

void List::reverse()
{
	Node *p = head->next;
	while (p->next != tail)	transfer(p, tail->pre, tail);
}

void List::swap(List &list)
{
	Node *temp = head;
	head = list.getHead();
	tail = list.getHead();
	list.setHead(temp);
}

void List::sort()
{
	List carry;
	List counter[64];
	int fill = 0;          
	while (head->next != tail)
	{
		carry.transfer(carry.getHead()->next, head->next, head->next->next);
		int i = 0;
		while (i < fill && counter[i].getHead()->next != counter[i].getHead())
		{
			counter[i].merge(carry);
			carry.swap(counter[i++]);
		}
		carry.swap(counter[i]);
		if (i == fill) ++fill;
	}
	for (int i = 1; i < fill; i++)
		counter[i].merge(counter[i-1]);
	swap(counter[fill - 1]);
}

#include <iostream>
#include "list.h"
using namespace std;


int main()
{
	int arr[] = {1,3,5,7,9};
	List myList1(arr,5);
	int arr2[] = { 2, 4, 6, 8 ,10};
	List myList2(arr2,5);
	myList1.transfer(myList1.find(1),myList2.find(2),myList2.getHead());
	//myList1.merge(myList2);
	//myList1.display();
	//myList1.reverse();
	myList1.sort();
	myList1.display();
	return 0;
}