Data Structures 之 链表

链表（Linked List），由一系列不必在内存中相连的结构组成。

按C的约定，函数的声明都在头文件中，具体的Node声明在.c文件中。    

adt.h

//按照C 的约定，作为类型的List表和Position以及函数原型都在头文件中

typedef int ElementType;

#ifndef ADT_H
#define ADT_H



struct Node;
typedef struct Node *PtrToNode; //定义指针指向结构体
typedef PtrToNode List;
typedef PtrToNode pNode;


bool IsEmpt(List L);
bool IsLast(pNode P, List L);
pNode Find(ElementType X, List L);
void Delete(ElementType X, List L);
pNode FindPrevious(ElementType X, List L);
void Insert(ElementType X, List L, pNode P);
void DeleteList(List L);


#endif // ADT_H_INCLUDED

结构体几点说明：

    1.Element 表示节点的数值，struct存储在内存上，而 pNode为指向struct的指针。

    2. typedef struct X{} X0 ; ， X0为类型struct X 的别名。

       struct Y{}y; , y 是struct Y的一个变量。

       

   

main.cpp

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include "adt.h"
#include "fatal.h"


using namespace std;


//定义链表中的节点
struct Node
{
    ElementType Element;
    struct Node *Next;
};

/*
struct Node *create()
{
    struct Node *head, *p;
    int x;
    head = NULL;
    cout << "Input Data " << endl;
    cin >> x;
    p = (struct Node *)malloc (sizeof (struct Node));
    p -> Element = x;
    p -> Next = NULL ;
    head = p;
    return head;
}
*/

struct Node *CreateList()
{
    int len;
    int val;
    struct Node *pHead, *pTail;
    pHead = (struct Node *)malloc (sizeof (struct Node));
    cout << "please input the length of the List : " << endl;
    cin >> len;
    pHead -> Element = len;
    pTail = pHead;
    pTail -> Next = NULL;
    for(int i=0; i < len; i++)
    {
        cout << "第" << i+1 <<"个节点的数值为：" ;
        cin >> val;
        struct Node *pNew = (struct Node *)malloc (sizeof (struct Node));
        pNew -> Element = val;
        pTail -> Next = pNew;
        pNew -> Next = NULL;
        pTail = pNew;
    }
    return pHead;

}

//遍历链表函数
void TraverList(List pHead)
{
    pNode p = pHead -> Next;
    while(NULL != p)
    {
        cout << p -> Element << "   ";
        p = p -> Next;
    }
    cout << endl;
}

//判断列表是否为空
bool IsEmpt(List L)
{
    if(L -> Next == NULL)
    {
        cout << "Empty !!!" << endl;
        return true;
    }
    else
    {
        cout << "NOT Empty !!! ";
        return false;
    }

}



//判断节点P 是不是链表的最后一个节点
bool IsLast(pNode P, List L)
{
    if(P->Next == NULL)
    {
        cout << "the last one " << endl;
        return true;
    }
    else
    {
        cout << "the Node P is Not the last !!!" << endl;
        return false;
    }
}

//查找X， 返回指针P

pNode Find(ElementType x, List L)
{
    pNode p;
    p = L -> Next;
    while(p != NULL && p -> Element != x)
    {
        p = p -> Next;

    }
    return p;
}

//查找前一个节点
pNode FindPrevious(ElementType x, List L)
{
    pNode p;
    p = L;
    while(p->Next != NULL && p->Next->Element !=x)
    {
        p = p->Next;
    }
    return p;
}

//删除一个节点
void Delete(ElementType x, List L)
{
    pNode p, q;
    p = FindPrevious(x,L);
    q = p -> Next;
    if( !IsLast(q,L))
    {
        p -> Next = q -> Next;
        free(q);
    }
    else
    {
        p -> Next = NULL;
        free(q);
    }
}

//插入一个节点
void Insert(ElementType x, List L, pNode P)
{
    pNode temp;

    temp = (struct Node *)malloc (sizeof (struct Node));
    if( temp == NULL)
    {
        FatalError("out of space ");
    }
    temp -> Element = x;
    temp -> Next = P-> Next;
    P -> Next = temp;
}


int main()
{
    cout << "the program  is starting ..." << endl;
    pNode pHead = NULL;

    pHead = CreateList();
    TraverList(pHead);
    IsEmpt(pHead);
    pNode p;

    p = Find(3,pHead);
    if(p)
    {
        cout << endl << "Find the element : ";
        cout << p -> Element << endl;
    }
    else {cout << endl << "Not Find !" << endl ;}

    Delete(2,pHead);

    pNode Pos ;
    Pos = Find(3,pHead);
    Insert(5, pHead, Pos);
    TraverList(pHead);
/*
    struct Node *p, *q;
    q = create();
    while(q){
        cout << q -> Element;
        p = q -> Next;

        free(q);
        q = p;
    }

*/
    return 0;
}

fff