演算法導論 迴圈單鏈表__演算法

迴圈單向鏈表 1. 迴圈單向鏈表如何?。

迴圈單向鏈表只是在單向鏈表的基礎上使尾結點指向頭結點。因為每次插入結點，新結點都是指向上一個結點當前的下一個結點。因此在單向鏈表的基礎上，我們使頭結點指向自身即可。
因此只需要在以前的博文單鏈表代碼中的建構函式初始化的時候，加上一行代碼，便做到了迴圈：
m_pHeadNode->SetNext(m_pHeadNode); 2. 實現（C++代碼）

//CircularSinglyLink.h#pragma once#include <assert.h>#include <stdio.h>template<typename ElemType>class Node{public:    Node(Node<ElemType>* pNext = NULL, ElemType* pData = NULL);    ElemType const& GetData() const;    void SetData(ElemType val) ;    Node<ElemType>* const& GetNext() const;    void SetNext(Node<ElemType>* val);private:    ElemType* m_pData;    Node<ElemType>* m_pNext;};template<typename ElemType>class CircularSinglyLink{public:    CircularSinglyLink();    unsigned int const& GetLength() const;    bool Insert(ElemType elem, unsigned int pos);    bool InsertByPosNode(ElemType elem, Node<ElemType>* posNode, Node<ElemType>** RetInsetNode = NULL);    bool Delete(unsigned int pos, ElemType* elem);    bool Search(unsigned int pos, ElemType* elem) const;    bool Visit(ElemType* elem, const unsigned int& pos) const;    bool Empty();    Node<ElemType>* HavaHeadNode();private:    Node<ElemType>* m_pHeadNode;    unsigned int m_length;};//————————————————————————————————//Node類的實現template<typename ElemType>Node<ElemType>::Node(Node<ElemType>* pNext /*= NULL*/, ElemType* pData /*= NULL*/)    :m_pNext(pNext),m_pData(pData){}template<typename ElemType>void Node<ElemType>::SetNext(Node<ElemType>* val){    m_pNext = val;}template<typename ElemType>Node<ElemType>* const& Node<ElemType>::GetNext() const{    return m_pNext;}template<typename ElemType>void Node<ElemType>::SetData(ElemType val){    m_pData = val;}template<typename ElemType>ElemType const& Node<ElemType>::GetData() const{    return *m_pData;}//————————————————————————————————//SinglyLink類實現template<typename ElemType>CircularSinglyLink<ElemType>::CircularSinglyLink()    :m_pHeadNode(new Node<ElemType>()),m_length(0){    m_pHeadNode->SetNext(m_pHeadNode);}template<typename ElemType>bool CircularSinglyLink<ElemType>::InsertByPosNode(ElemType elem, Node<ElemType>* posNode, Node<ElemType>** RetInsetNode /*= NULL*/){    Node<ElemType>* insertNode = new Node<ElemType>(posNode->GetNext(),new ElemType(elem));    posNode->SetNext(insertNode);    ++m_length;    *RetInsetNode = insertNode;    return true;}template<typename ElemType>bool CircularSinglyLink<ElemType>::Insert(ElemType elem, unsigned int pos){    if (pos > GetLength() || pos < 0)    {        assert(false && "Error: SinglyLink's insert pos is out of range!\n");        return false;    }    for(Node<ElemType>* pCurrentNode = m_pHeadNode; pCurrentNode != NULL; pCurrentNode = pCurrentNode->GetNext())    {        if (pos-- == 0)        {            Node<ElemType>* insertNode = new Node<ElemType>(pCurrentNode->GetNext(),new ElemType(elem));            pCurrentNode->SetNext(insertNode);            ++m_length;            return true;        }    }    assert(false && "Error: SinglyLink Insert failed for unknow reason!");    return false;}template<typename ElemType>bool CircularSinglyLink<ElemType>::Delete(unsigned int pos, ElemType* elem){    if (pos >= GetLength() || pos < 0)    {        assert(false && "Error: SinglyLink's delete pos is out of range!\n");    }    for(Node<ElemType>* pCurrentNode = m_pHeadNode; pCurrentNode != NULL; pCurrentNode = pCurrentNode->GetNext())    {        if (pos-- == 0)        {            Node<ElemType>* deleteNode = pCurrentNode->GetNext();            pCurrentNode->SetNext(deleteNode->GetNext());            *elem = deleteNode->GetData();            delete deleteNode;            --m_length;            return true;        }    }    assert(false && "Error: SinglyLink pos delete failed for unknow reason!");    return false;}template<typename ElemType>unsigned int const& CircularSinglyLink<ElemType>::GetLength() const{    return m_length;}template<typename ElemType>bool CircularSinglyLink<ElemType>::Search(unsigned int pos, ElemType* elem) const{    if (pos >= GetLength() || pos < 0)    {        assert(false && "Error: SinglyLink's search pos is out of range!\n");    }    for(Node<ElemType>* pCurrentNode = m_pHeadNode; pCurrentNode != NULL; pCurrentNode = pCurrentNode->GetNext())    {        if (pos-- == 0 && (pCurrentNode->GetNext() != NULL) )        {            *elem = pCurrentNode->GetNext()->GetData();            return true;        }    }    return false;}template<typename ElemType>bool CircularSinglyLink<ElemType>::Visit(ElemType* elem, const unsigned int& pos) const{    if (pos >= GetLength() || pos < 0)    {        return false;    }    return Search(pos,elem);}template<typename ElemType>bool CircularSinglyLink<ElemType>::Empty(){    return !m_length;}template<typename ElemType>Node<ElemType>* CircularSinglyLink<ElemType>::HavaHeadNode(){    return m_pHeadNode;}

//Util.h#pragma oncenamespace Util{    template<typename T>    void PrintMemory(const T& dateStruct, unsigned int size)    {        cout << "PrintMemory: ";        for (int i = 0; i != size; i++)        {            ElemType tempElem;            if (!dateStruct.Visit(&tempElem,i))            {                printf("\n");                return;            }            printf("%d ",tempElem);        }        printf("\n");    }}

//main.cpp#include "Util.h"#include "CircularSinglyLink.h"#include <iostream>using namespace std;typedef int ElemType;int main(){    CircularSinglyLink<int> testCircularSinglyLink;    cout << "testCircularSinglyLink is " << (testCircularSinglyLink.Empty() ? "Empty." : "Not Empty.") << endl;    Util::PrintMemory(testCircularSinglyLink,testCircularSinglyLink.GetLength());    for (int i = 0; i != 5; i++)    {        testCircularSinglyLink.Insert(i+1,i);        cout << "\nInsert:" << i << endl;        cout << "testCircularSinglyLink is " << (testCircularSinglyLink.Empty() ? "Empty." : "Not Empty.") << endl;        Util::PrintMemory(testCircularSinglyLink,testCircularSinglyLink.GetLength());    }    for (int i = 0; i != 2; i++)    {        ElemType tempElem;        testCircularSinglyLink.Delete(i,&tempElem);        cout << "\nDelete:" << tempElem << endl;        cout << "testCircularSinglyLink is " << (testCircularSinglyLink.Empty() ? "Empty." : "Not Empty.") << endl;        Util::PrintMemory(testCircularSinglyLink,testCircularSinglyLink.GetLength());    }    return 0;}

3. 程式運行結果

testCircularSinglyLink is Empty.
PrintMemory:

Insert:0
testCircularSinglyLink is Not Empty.
PrintMemory: 1

Insert:1
testCircularSinglyLink is Not Empty.
PrintMemory: 1 2

Insert:2
testCircularSinglyLink is Not Empty.
PrintMemory: 1 2 3

Insert:3
testCircularSinglyLink is Not Empty.
PrintMemory: 1 2 3 4

Insert:4
testCircularSinglyLink is Not Empty.
PrintMemory: 1 2 3 4 5

Delete:1
testCircularSinglyLink is Not Empty.
PrintMemory: 2 3 4 5

Delete:3
testCircularSinglyLink is Not Empty.
PrintMemory: 2 4 5