线性表——（2）单向链表

// "ListNode.h"

#include <iostream>
using namespace std;

template<class T>
class ListNode
{
public:
    ListNode():p_next(NULL){ }
    ListNode(const T item, ListNode<T>* next = NULL):data(item), p_next(next){ }
    T GetData();
protected:
    T data; // 存放节点值
    ListNode* p_next;   // 存放后继地址
};

template<class T>
T ListNode<T>::GetData()
{
    return this->data;
}

// SingleList.h

#include "ListNode.h"

template<class T>
class SingleList
{
public:
    SingleList();
    ~SingleList();
    int Length();   // 链表长度
    void Clear();   // 清空链表
    int Find(int n, T &targ);   // 查找n号节点，值存入targ
    int Insert(int n, T targ);  // 将targ插入n号位置
    int Delete(int n);  // 删除第n个元素


private:
    ListNode<T>* head;  // 存储一个T的节点指针head
};

template<class T>
inline SingleList<T>::SingleList()
{
    head = new ListNode<T>();
}

template<class T>
inline SingleList<T>::~SingleList()
{
    Clear();
    delete head();
}

template<class T>
int SingleList<T>::Length()
{
    ListNode<T>* p = head->p_next;
    int count = 0;
    while (p != NULL) {
        ++count;
        p = p->p_next;
    }
    return count;
}

template<class T>
void SingleList<T>::Clear()
{
    ListNode<T>* pdel;  // 从前到后依次删除连接,直到指向NULL的指针也被删除
    while (head->p_next != NULL) {

        pdel = head->p_next;
        head->p_next = pdel->p_next;
        delete pdel;
    }
}

template<class T>
int SingleList<T>::Find(int n, T & targ)
{
    if (n < 0 || n > Length()) {
        cout << "Illegal opration!" << endl;
        return 0;
    }
    ListNode<T>* p = head->p_next;
    for (int i = 0; i <= n; && p ++i) {
        p = p->p_next;

    }
    if (p == NULL) {
        cout << "overflow" << endl;
        return 0;
    }
    targ = p->data;
    return 1;
}

template<class T>
int SingleList<T>::Insert(int n, T targ)
{
    if (n < 0 || n > Length()) {
        cout << "Illegal n" << endl;
        return 0;
    }
    ListNode<T>* p = head;
    ListNode<T>* p_new = new ListNode<T>(targ, NULL);
    if (p_new == NULL) {
        cout << "Node Error" << endl;
        return 0;
    }
    for (int i = 0; i < n; ++i) {
        p = p->p_next;
    }
    p_new->p_next = p->p_next;
    p_next = p_new;
    return 1;
}

template<class T>
int SingleList<T>::Delete(int n)
{
    if (n < 0 || n > Length()) {
        cout << "Illegal n" << endl;
        return 0;
    }
    ListNode<T>* p = head;
    ListNode<T>* pdel;
    for (int i = 0; i < n && p->p_next; ++i) {
        p = p->p_next;
    }
    pdel = p;
    p->p_next = pdel->p_next;
    T data = pdel->data;
    delete pdel;
    return 1;
}