【c++版數據結構】之循環雙鏈表的實現（帶頭結點以及尾節點）

所實現的循環雙鏈表的結構如下圖所示：

循環雙鏈表的實現，和第一篇文章單鏈表的實現思想大致相同點擊打開鏈接，具體思想參考該文章。本篇文章在構建節點的同時，初始化構建節點的前驅和後繼，具體細節參考下列代碼

頭文件：DCList.h

#ifndef DCLIST_H
#define DCLIST_H

#include<iostream>
#include<cstdlib>
#include<cassert>
using namespace std;

typedef enum{FALSE,TRUE}Status;

template<class Type>
class List;

template<class Type>
class ListNode
{
	template<class Type>
	friend class List;
private:
	Type data;
	ListNode<Type> *prio;
	ListNode<Type> *next;
public:
	ListNode() :data(Type()),prio(NULL), next(NULL){}
	ListNode(const Type x, ListNode<Type> *p = NULL, ListNode<Type> *n = NULL)
		:data(x), prio(p), next(n){}
	Type getData()const { return data; }
};

template<class Type>
class List
{
private:
	ListNode<Type> *first;
	ListNode<Type> *last;
	size_t          size;
public:
	ListNode<Type>* _BuyNode(const Type x, ListNode<Type> *p = NULL, ListNode<Type> *n = NULL)
	{
		ListNode<Type> *s = new ListNode<Type>(x, p, n);
		assert(s != NULL);
		return s;
	}
	List()
	{
		ListNode<Type> *s = _BuyNode(0, NULL, NULL);
		first = last = s;
		last->next = first;
		size = 0;
	}
	~List()
	{
		destory();
	}
	Status push_back(const Type &x)
	{
		ListNode<Type> *s = _BuyNode(x, last, first);
		last->next = s;
		last = s;
		size++;
		return TRUE;
	}
	void show_list()
	{
		ListNode<Type> *s = first->next;
		while (s != first)
		{
			cout << s->data << "->";
			s = s->next;
		}
		cout << "Nul." << endl;
	}
	Status push_front(const Type &x)
	{
		ListNode<Type> *s = _BuyNode(x, first, first->next);
		if (size == 0)
		{
			first->next = s;
			last = s;
			last->next = first;
		}
		else
		{
			first->next->prio = s;
			first->next = s;
		}
		size++;
		return TRUE;
	}
	Status pop_back()
	{
		if (size == 0)
		{
			cout << "循環雙鏈表已空，無法尾刪" << endl;
			return FALSE;
		}
		ListNode<Type> *s = last->prio;
		delete last;
		last = s;
		last->next = first;
		size--;
		return TRUE;
	}
	Status pop_front()
	{
		if (size == 0)
		{
			cout << "循環雙鏈表已空，無法頭刪" << endl;
			return FALSE;
		}
		ListNode<Type> *s = first->next;
		if (size == 1)
		{
			last = first;
			last->next = first;
		}
		else
		{
			first->next = s->next;
			s->next->prio = first;
		}
		delete s;
		size--;
		return TRUE;
	}
	Status insert_val(const Type &x)
	{
		ListNode<Type> *s = first;
		while (s->next != first && s->next->data < x)
		{
			s = s->next;
		}
		if (s->next == first)//直接尾插即可
		{
			ListNode<Type> *p = _BuyNode(x, last, first);
			last->next = p;
			last = p;
		}
		else//找到了前驅，在其之後插入即可
		{
			ListNode<Type> *p = _BuyNode(x, s, s->next);
			s->next->prio = p;
			s->next = p;
		}
		size++;
		return TRUE;
	}
	size_t lenth()
	{
		return size;
	}
	ListNode<Type>* find(const Type &x)
	{
		ListNode<Type> *s = first->next;
		while (s != first && s->data != x)
		{
			s = s->next;
		}
		if (s == first)
			return NULL;
		else
			return s;
	}
	Status delete_val(const Type &x)
	{
		ListNode<Type> *s = find(x);
		if (s == NULL)
		{
			cout << "該元素不存在，無法刪除" << endl;
			return FALSE;
		}
		if (s == last)
		{
			ListNode<Type> *p = last->prio;
			delete last;
			last = p;
			last->next = first;
		}
		else
		{
			ListNode<Type> *q = s->next;
			s->data = q->data;
			s->next = q->next;
			q->next->prio = s;
			delete q;
		}
		size--;
		return TRUE;	
	}
	void sort()
	{
		if (size == 0 || size == 1)
			return;
		ListNode<Type> *s = first->next;
		ListNode<Type> *p = s->next;
		last = s;
		last->next = first;
		while (p != first)
		{
			s = p;
			p = p->next;

			ListNode<Type> *q = first;
			while (q->next != first && q->next->data < s->data)
			{
				q = q->next;
			}
			if (q->next == first)
			{
				last->next = s;
				s->prio = last;
				last = s;
				last->next = first;
			}
			else
			{
				s->next = q->next;
				q->next->prio = s;
				q->next = s;
				s->prio = q;
			}
		}
	}
	void reverse()
	{
		if (size == 0 || size == 1)
			return;
		ListNode<Type> *s = first->next;
		ListNode<Type> *p = s->next;
		last = s;
		last->next = first;
		while (p != first)
		{
			s = p;
			p = p->next;

			s->next = first->next;
			first->next->prio = s;
			first->next = s;
			s->prio = first;
		}
	}
	void clear()
	{
		if (size == 0)
			return;
		ListNode<Type> *s = first->next;
		while (s != first)
		{
			if (size == 1)
			{
				last = first;
				last->next = first;
			}
			else
			{
				first->next = s->next;
				s->next->prio = first;
			}
			delete s;
			size--;
			s = first->next;//爲下一次刪除做準備
		}
	}
	void destory()
	{
		clear();
		delete[] first;
		first = last = NULL;
	}
	ListNode<Type>* next(ListNode<Type> *s)
	{
		if (s == last)
			return NULL;
		else
			return s->next;
	}
	ListNode<Type>* prio(ListNode<Type> *s)
	{
		if (s == first->next) //-------------->第一個節點沒有前驅，返回NULL
			return NULL;
		else
			return s->prio;
	}
};
#endif

測試文件main.cpp

#include"DCList.h"
int main()
{
	List<int> mylist;
	int item;
	int n;
	int select = 1;
	//ListNode<int> *p;
	while (select)
	{
		cout << "*************************************** *" << endl;
		cout << "*[1] push_back           [2] push_front *" << endl;
		cout << "*[3] show_list           [4] pop_back   *" << endl;
		cout << "*[5] pop_front           [6] insert_val *" << endl;
		cout << "*[7] lenth               [8] find       *" << endl;
		cout << "*[9] merge               [10] delete_val*" << endl;
		cout << "*[11] sort               [12] reverse   *" << endl;
		cout << "*[13] next               [14] clear     *" << endl;
		cout << "*[15] prio               [0] quit_system*" << endl;
		cout << "請選擇：>";
		cin >> select;
		switch (select)
		{
		case 1:
			cout << "請輸入要插入的元素（-1結束):>";
			while (cin >> item, item != -1)
			{
				mylist.push_back(item);
			}
			break;
		case 2:
			cout << "請輸入要插入的元素（-1結束）:>";
			while (cin >> item, item != -1)
			{
				mylist.push_front(item);
			}
			break;
		case 3:
			mylist.show_list();
			break;
		case 4:
			mylist.pop_back();
			break;
		case 5:
			mylist.pop_front();
			break;
		case 6:
			cout << "請輸入要插入的元素：";
			cin >> item;
			mylist.insert_val(item);
			break;
		case 7:
			cout << "長度爲：" << mylist.lenth() << endl;
			break;
		case 8:
			cout << "請輸入要查找的元素：";
			cin >> item;
			if (mylist.find(item))
				cout << "it's found" << endl;
			else
				cout << "it's not exist" << endl;
			break;
		case 9:
			cout << "請輸入要刪除的位置：";
			cin >> n;
			//mylist.delete_pos(n,item);
			break;
		case 10:
			cout << "請輸入要刪除的元素：";
			cin >> item;
			mylist.delete_val(item);
			break;
		case 11:
			mylist.sort();
			break;
		case 12:
			mylist.reverse();
			break;
		case 14:
			mylist.clear();
			break;
		default:
			break;
		}
	}
	system("pause");
	return 0;
}