数据结构：实验二线性表综合实验③双链表

一.实验目的
巩固线性表的数据结构的存储方法和相关操作，学会针对具体应用，使用线性表的相关知识来解决具体问题。

二.实验内容
通过双链表建立一个由n个学生成绩的顺序表，n的大小由自己确定，每一个学生的成绩信息由自己确定，实现数据的对表进行插入、删除、查找等操作。分别输出结果。

三.实验报告
1.实验代码如下：

#include<iostream>  
using namespace std;

template <typename T>
class  Node
{
public:
    T data;
    Node<T> *prior;
    Node<T> *next;
};

template <typename T>
class DLL {
public:
    DLL();
    DLL(T score[], int n);  //有参构造函数  
    ~DLL();  //析构函数  
    int Length(); //返回单链表长度  
    void insert(int i, T x); //插入操作，在位置i插入元素  
    T get(int i);  //按位查找  
    int locate(T x);  //按值查找  
    T Delete(int i);  //删除操作  
    void print();  //遍历操作  
private:
    Node<T> *first;  //双链表的头指针  
    int length;   //链的长度计数  
};

template <typename T>
DLL<T>::DLL(T score[], int n)
{
    length = 0;
    first = new Node<T>;
    first->next = NULL;
    first->prior = NULL;
    for (int i = n-1; i>=0; i--)
    {
        Node<T> *s = new Node<T>;
        s->data = score[i];
        s->next = first->next;
        first->next = s;
    }
}

template <typename T>
DLL<T>::~DLL()
{
    while (first->next != first->prior)
    {
        //临时指针，存储即将释放的节点的指针  
        Node<T> *temp = first;
        //脱链  
        first->prior->next = first->next;
        first->next->prior = first->prior;
        //头指针后移  
        first = first->next;
        //释放内存  
        delete temp;
    }
    delete first;
}

template<typename T>
int DLL<T>::Length()
{
    Node<T> *p; int count;
    p = first->next;
    count = 0;
    while (p != NULL)
    {
        p = p->next;
        count++;
    }
    return length;
}

template <typename T>
void DLL<T>::insert(int i, T x)
{
    Node<T>*p, *s; int count;
    p = first;
    count = 0;
    while (p != NULL&&count<i - 1)
    {
        p = p->next;
        count++;
    }
    if (p == NULL) throw"位置";
    else
    {
        s = new Node<T>;
        s->data = x;
        s->next = p->next;
        p->next = s;
    }
}

template <typename T>
T DLL<T>::get(int i)
{
    Node<T> *p; int count; count = 1;
    p = first->next;
    while (p != NULL&&count<i)
    {
        p = p->next; count++;
    }
    if (p == NULL)throw"位置非法";
    else return p->data;
}

template <typename T>
int DLL<T>::locate(T x)
{
    Node<T> *p; int count;
    p = first->next; count = 1;
    while (p != NULL)
    {
        if (p->data == x) return count;
        p = p->next;
        count++;
    }
    return 0;
}

template <typename T>
T DLL<T>::Delete(int i)
{
    Node<T> *p, *q;
    p = first->next; int count, x; count = 1;
    while (p != NULL&&count<i - 1)
    {
        p = p->next; count++;
    }
    if (p == NULL || p->next == NULL) throw"位置非法";
    else
    {
        q = p->next;
        x = q->data;
        if (p->next != NULL)
        {
            if (q->next != NULL)
                q->next->prior = p;
            else
            {
                p->next = NULL;
                p->next = q->next;
                delete q;
                q = NULL;
                return x;
            }
        }
        p->next = q->next;
        delete q;
        q = NULL;
        return x;
    }
}

template <typename T>
void DLL<T>::print()
{
    Node<T> *p;
    p = first->next;
    while (p->next != NULL)
    {
        cout << p->data << " ";
        p = p->next;
    }
    cout << p->data << endl;
}

void main()
{
    int score[5] = { 66,71,68,45,93 };
    DLL<int>student(score,5);
    cout << "学生成绩" << endl;
    student.print();
    cout << endl << "在位置3插入成绩63，插入后结果如下：" ;
    student.insert(3,63);
    student.print();
    cout<< endl << "在位置2删除成绩为：" << student.Delete(2);
    cout << "删除后结果如下:"; student.print();
    cout<< endl << "位置3的成绩为：" << student.get(3);
    cout<< endl << "成绩71所在位置为：" << student.locate(71) ;
}

2.实验结果

四.实验总结
通过双链表建立一个由5个学生成绩的顺序表，学生成绩分别为66, 71, 68, 45, 93 ，对表在位置3插入63，插入后学生成绩为66, 71, 63，68, 45, 93 ，删除位置2的成绩71，删除后为66, 63, 68, 45, 93 .