Question

我使用以下源代码

创建了一个链接列表程序

#include <iostream>

using namespace std;

struct Node
{
    int data;
    Node *next;
};

struct HeadNode
{
    int count;
    Node *headPtr;
};

class LinkedList
{
    public:
            LinkedList();
            ~LinkedList();

            void addToHead( int );
            bool removeFromHead();

//          bool addToTail ( int );
//          bool removeFromTail();

            void addNode ( int );
            bool deleteNode ( int );
            void deleteAllNodes();

            bool isEmpty();
            int getNoOfNodes();

            void displayAllNodes();

    private:
        int dataCmp ( int, int );
        void displayNode ( Node* );

        HeadNode head;
};

LinkedList::LinkedList()
{
    head.count = 0;
    head.headPtr = NULL;
    return;
}

LinkedList::~LinkedList()
{
    deleteAllNodes();
    return;
}

void LinkedList::addToHead ( int newData )
{
    Node *pNew = new Node;
    pNew -> data = newData;
    pNew -> next = head.headPtr;
    head.headPtr = pNew;
    head.count++;
}

bool LinkedList::removeFromHead()
{
    bool exit;
    Node *temp;

    if ( head.headPtr )
    {
        temp = head.headPtr;
        head.headPtr = head.headPtr -> next;
        delete temp;
        head.count--;
        exit = true;        // returns true if it's successful
    }
    else
        exit = false;       // returns false if it's not successful
    return exit;
}

/*
bool LinkedList::addToTail( int )
{

}
bool Linked::removeFromTail();
{

}
*/

void LinkedList::addNode ( int newData )
{
    Node *pNew = new Node,
         *pPre = NULL,
         *pCur = head.headPtr;
    pNew -> data = newData;

    while ( pCur && dataCmp( pNew -> data, pCur -> data ) >= 0 )
        {
            pPre = pCur;
            pCur = pCur -> next;
        }

    if ( pPre )
    {
        pNew -> next = pPre -> next;
        pPre -> next = pNew;
        head.count++;
    }
    else
    {
        pNew -> next = head.headPtr;
        head.headPtr = pNew;
        head.count++;
    }
}

bool LinkedList::deleteNode( int data )
{
    bool exit;
    Node *pPre = NULL,
         *pCur = head.headPtr;

    while ( pCur && dataCmp( pCur -> data, data ) < 0 )
    {
        pPre = pCur;
        pCur = pCur -> next;
    }

    if ( pCur && dataCmp( pCur -> data, data ) == 0 )
    {
        if ( pPre )
        {
            pPre -> next = pCur -> next;
            delete pCur;
            head.count--;
            exit = true; // return true if successful
        }
        else
        {
            head.headPtr = pCur -> next;
            delete pCur;
            head.count--;
            exit = true; // return true if successful
        }
    }
    else
        exit = false; // return false if unsuccessful

    return exit;
}

void LinkedList::deleteAllNodes()
{
    Node *temp;

    while ( head.headPtr )
    {
        temp = head.headPtr;
        head.headPtr = head.headPtr -> next;
        delete temp;
        head.count--;
    }

    return;
}

bool LinkedList::isEmpty()
{
    return head.count == 0;
}


int LinkedList::getNoOfNodes()
{
    return head.count;
}

void LinkedList::displayAllNodes()
{
    Node *pCur = head.headPtr;
    int nodeCount = 1;

    while ( pCur )
    {
        cout << "Node " << nodeCount << ": ";
        displayNode( pCur );
        cout << endl;

        nodeCount++;
        pCur = pCur -> next;
    }

    return;
}

int LinkedList::dataCmp( int value0, int value1 )
{
    int exit = 0;

    if ( value0 < value1 )
        exit = -1;
    else if ( value0 > value1 )
        exit = 1;

    return exit;
}

void LinkedList::displayNode( Node *node )
{
    cout << node -> data;
    return;
}

void printMenu()
{
    cout << "1. Add to head" << endl;
    cout << "2. Remove from head" << endl;
    cout << "3. Add node " << endl;
    cout << "4. Delete node" << endl;
    cout << "5. Delete all nodes" << endl;
    cout << "6. Is the list empty?" << endl;
    cout << "7. Get number of nodes" << endl;
    cout << "8. Display all nodes" << endl;
    cout << "9. Quit" << endl;
}

int getChoice()
{
    int choice;

    cout << "Select choice: ";
    cin >> choice;
    cin.clear();
    cin.ignore( 200, '\n' );
    return choice;
}

int getData()
{
    int data;

    cout << "Enter data: ";
    cin >> data;
    cin.clear();
    cin.ignore( 200, '\n' );

    return data;
}

void processChoice( int choice, LinkedList& list )
{
    int data;
    bool opStatus;

    switch ( choice )
    {
        case 1: data = getData();
            list.addToHead( data );
            break;
        case 2: if ( list.removeFromHead() )
            {
                cout << "Removed node from head" << endl;
            }
            else
                cerr << "List is empty" << endl;
            break;
        case 3: data = getData();
            list.addNode( data );
            cout << "Node " << data
                 << " added";
            cout << endl;
            break;
        case 4: if ( !list.isEmpty() )
            {
                data = getData();
                if ( list.deleteNode( data ) )
                {
                    cout << "Node " << data
                         << " deleted";
                    cout << endl;
                }
                else
                    cerr << "Node not found" << endl;
            }
            else
                cerr << "List is empty" << endl;
            break;
        case 5: list.deleteAllNodes();
            cout << "All nodes deleted" << endl;
            break;
        case 6: cout << ( list.isEmpty() ? 
                      "List is empty" : "List is not empty" );
            cout << endl;
            break;
        case 7: cout << "No. of nodes: "
                 << list.getNoOfNodes();
            cout << endl;
            break;
        case 8: list.displayAllNodes();
            break;
        default: cout << "Invalid choice" << endl;
    }

}

int main()
{
    LinkedList list;
    int choice;
    do
    {
        printMenu();
        choice = getChoice();

        if ( choice != 9 )
            processChoice( choice, list );

    } while ( choice != 9 );



    return 0;
}

如何修改我的代码，而不是按Value删除，以便按索引删除节点？

Answer 1

添加一个带有索引值的deleteNodeByIndex函数，然后你可以执行相同的删除操作，除了删除给定索引处的项目而不是测试值匹配。

编辑：

你已经按照数据删除了一个节点，你已经在那里了一半。唯一的区别是，不是遍历每个项目并测试数据值，而是计算您迭代完毕的项目数量，直到达到要删除的索引。

bool LinkedList::deleteNodeByIndex( int index )
{
    bool exit;
    Node *pPre = NULL,
         *pCur = head.headPtr;
    int currentIndex = 0;

    while ( pCur )
    {
        // Here we just loop until we reach our desired index.
        if (currentIndex == index)
        {
            break;
        }

        // Increment the current index and pCur to the next item.
        currentIndex++;
        pPre = pCur;
        pCur = pCur -> next;
    }

    // If pCur is still valid at this point, it means we broke at the
    // proper place and pCur should be at the proper index.
    if ( pCur )
    {
        if ( pPre )
        {
            pPre -> next = pCur -> next;
            delete pCur;
            head.count--;
            exit = true; // return true if successful
        }
        else
        {
            head.headPtr = pCur -> next;
            delete pCur;
            head.count--;
            exit = true; // return true if successful
        }
    }
    else
        exit = false; // return false if unsuccessful

    return exit;
}

Answer 2

如何修改我的代码，以便按索引删除节点？

除非您从列表的头部开始计算节点，否则您无法知道链接列表中节点的索引。例如，如果要删除列表中的第五个节点，则需要从头开始并按照next指针进行操作，直到到达第四个节点。然后你只需要保存一个指向第五个节点的指针，将第四个节点的next设置为第五个节点的next，然后使用你刚刚保存的指针删除第五个节点。 / p>

Answer 3

这与删除节点的方法相同，除了您还需要实现索引系统。

例如.... enter image description here

增加大小并在每个新值之后。在添加时根据大小添加新索引。

你必须明白这将是一个0（n）操作。与真正的链接列表O（1）相比，但是你正在对你的删除操作进行O（n）操作，所以谁在乎呢！

只是把它放在这里因为它是一些关于使用链接列表进行索引的好信息。

Link List info

按索引删除？

3 个答案: