数据结构学习第四天

19:41:25 2019-08-19

继续学习

链表的游标实现

Cursor.h

#ifndef _CURSOR_H
#define _CURSOR_H
#define Size 50     
#define Null 0   //当Next为0 类似于空指针
typedef int PtrToNode;
typedef PtrToNode List;
typedef PtrToNode Position;
struct Node
{
    int Element;
    Position Next;
};
extern struct Node CursorSpace[Size];
void InitializeCursorSpace();  //初始化空间

List MakeEmpty(List L);     //建一个空的表头
int IsEmpty(const List L);    
int IsLast(const Position P, const List L);
Position Find(int Element, const List L);
void Delete(int Element, List L);
Position FindPrevious(int Element, const List L);
void Insert(int Element, List L, Position P);  //插入到P元素之前
void DeleteList(List L);                    //删除表
Position Header(List L);
Position First(List L);
int Retrive(const Position P);            //取回元素
Position CursorAlloc();
void FreeCursor(Position P);
#endif // !_CURSOR_H

Cursor.c

#include"Cursor.h"
#include<stdio.h>

struct Node CursorSpace[Size];
Position CursorAlloc()  //从已有空间中 申请空间
{
    Position P;
    P = CursorSpace[0].Next;   //每次都申请从第一个元素开始
    if (P == 0)
    {
        printf("申请失败");
        return 0;
    }
    CursorSpace[0].Next = CursorSpace[P].Next;
    CursorSpace[P].Next = Null;     //将申请的空间初始化
    return P;
}

void FreeCursor(Position P)
{
    CursorSpace[P].Element = 0;
    CursorSpace[P].Next = CursorSpace[0].Next;
    CursorSpace[0].Next = P;
}
void InitializeCursorSpace()   
{
    for (int i = 0; i < Size - 1; i++)
    {
        CursorSpace[i].Element = 0;   
        CursorSpace[i].Next = i + 1;
    }
    CursorSpace[Size - 1].Next = 0;    //尾部连接在了头部   访问位置为0的元素是非法的
    CursorSpace[Size - 1].Element = 0;
}
List MakeEmpty(List L)
{
    L = CursorAlloc();
    return L;
}
int IsEmpty(const List L)
{
    return    CursorSpace[L].Next == Null;
}
int IsLast(const Position P, const List L)
{
    return CursorSpace[P].Next == Null;
}
Position Find(int Element, const List L)
{
    Position P = CursorSpace[L].Next;
    /*while (P!=Null)
    {
        if (CursorSpace[P].Element ==Element)
            return P;
        P = CursorSpace[P].Next;
    }
    return Null;*/
    //下面这个版本更加简化
    while (P && CursorSpace[P].Element != Element)
    {
        P = CursorSpace[P].Next;
    }
    return P;    //返回值为0说明 没有找到
}

void Delete(int Element, List L)
{
    Position P1, P2;
    P1 = P2 = FindPrevious(Element, L);   //找到前置元素
    if (P1 == 0)
    {
        printf("该元素不存在");
        return;
    }
    P2 = CursorSpace[P1].Next;
    //CursorSpace[P1].Next = CursorSpace[CursorSpace[P1].Next].Next;
    CursorSpace[P1].Next = CursorSpace[P2].Next;
    FreeCursor(P2);
}

Position FindPrevious(int Element, const List L)
{
    Position P = L;
    /*while (CursorSpace[P].Next!=Null)
    {
        if (CursorSpace[CursorSpace[P].Next].Element == Element)
            return P;
        P = CursorSpace[P].Next;
    }
    return Null;*/
    while (CursorSpace[P].Next && CursorSpace[CursorSpace[P].Next].Element != Element)
    {
        P = CursorSpace[P].Next;
    }
    return P;
}
void Insert(int Element, List L, Position P)  //插入P前
{
    Position P1 = CursorAlloc();
    CursorSpace[P1].Element = Element;
    CursorSpace[P1].Next = P;  
    Position P2 = FindPrevious(CursorSpace[P].Element, L);
    CursorSpace[P2].Next = P1;
}
void DeleteList(List L)
{
    Position P1, P2;
    P1 = P2 = CursorSpace[L].Next;
    while (P2 != Null)
    {
        P2 = CursorSpace[P1].Next;
        FreeCursor(P1);
        P1 = P2;
    }
}
int Retrive(const Position P)
{
    return CursorSpace[P].Element;
}
Position Header(List L)
{
    return L;
}
Position First(List L)
{
    return CursorSpace[L].Next;
}

main.c

#include<stdio.h>
#include"Cursor.h"
int main()
{
    InitializeCursorSpace();   //初始化
    int L = 0;
    L=MakeEmpty(L);
    printf("%d
",  IsEmpty(L));   
    printf("%d
", CursorSpace[L].Element);
    int P = CursorAlloc();
    CursorSpace[P].Element = 20;
    CursorSpace[L].Next = P;
    printf("%d
", CursorSpace[P].Element);
    Insert(25, L, P);
    printf("%d
", CursorSpace[CursorSpace[L].Next].Element);
    printf("%d
", Retrive(P));
    printf("%d
", CursorSpace[P].Next);
    printf("%d
", Find(20, L));
    Delete(20, L);
    Delete(25, L);
    printf("%d
", CursorSpace[L].Next);
    return 0;
}

之前几天写完都没有测试过 今天突然想测试下 出了一堆bug

之后每个写完都要去测试 前面的会抽时间补上的

其实只有一个bug 原因是我对编译过程不了解 一个变量声明在了头文件中 导致重复定义  

看来得尝试用linux编程了