C语言实现单向链表及其各种排序(含快排,选择,插入,冒泡)

作者在 2014-11-02 00:10:46 发布以下内容

#include<stdio.h>
#include<malloc.h>
#define LEN sizeof(struct Student)
struct Student                //结构体声明
{
 long num;
 int score;
 struct Student* next;
};
int n;

struct Student* creat()           //创建单向链表
{
 struct Student *head=NULL, *p_before, *p_later;
 p_before = p_later = (struct Student*) malloc(LEN);
 scanf_s("%ld%d", &p_before->num, &p_before->score);
 while (p_before->num!=0)
 {
  n++;
  if (n == 1) head = p_before;
  else p_later->next = p_before;
  p_later = p_before;
  p_before = (struct Student*) malloc(LEN);
  scanf_s("%ld%d", &p_before->num, &p_before->score);
 }
 p_later->next = NULL;
 free(p_before);
 return head;
}

struct Student* sort(struct Student* list)               //冒泡排序,当初写的是内容交换而不是指针交换,我知道这不是好的做法,但日子一久,当下没时间和热情改了,大家原谅,
{                                                                            //等有时间了一定改
 struct Student *p, *q;
 int temp1,i;
 long temp2;
 for (p = list, i =1; i < n;i++,p=p->next)
  for (q = p->next;q!= NULL;q=q->next)  
   if (p->score < q->score)
   {
    temp1 = p->score;
    p->score = q->score;
    q->score = temp1;
    temp2 = p->num;
    p->num = q->num;
    q->num = temp2;
   }
   return list;
}

struct Student* sort1(struct Student* h)                //插入排序(下边这堆注释是当初写完代码后又分析时加的,这里必须承认,我参考了网上的一些代码。这里大家要是看不      
{                                                                            //懂或是不想看,就略过吧。还有,这里“结点”写成“节点”了,纠正一下,不好意思
 struct Student *f, *t, *p=NULL, *q;
 f = h->next;                  //f指向旧链的第一个节点,即等待在新链中“安家落户”(插入)的节点
 h->next = NULL;               //将原链的第一个节点单拿出来作为新链(待插入链)的第一个节点,默认此节点是关键值最大的节点
 while (f!=NULL)    //当f=NULL,旧链中的节点都插入到了新链,排序完成
 {
  for (t = f, q = h; (q != NULL && (q->score > t->score)); p = q, q = q->next);//t和f同指,当找到插入位置,f指向旧链的下一个节点时,用t来进行
                                                    //插入操作;q先指向新链的第一个节点,q不断在新链中后移,以找到f(即t)所指节点的插入位置
                                                    //p作为q的前驱,用来完成插入。整个语句的作用是:在新链遍历完(q != NULL)的前提下,在新
                                                    //链中找到第一个关键值比f(即t)所指节点关键值小的节点,毫无疑问,q的前驱,即p(如果有的
                                                    //话)的关键值一大于定f(即t)所指节点关键值(否则q怎么会后移到当前位置呢?);如果没有,
                                                    //那说明当前新链的头节点关键值比f(即t)所指节点关键值小;如果最后q = NULL了,说明当前新
                                                    //链的最后一个节点(此时p正指向它)的关键值都比f(即t)所指节点关键值大。不管哪种情况,f
                                                    //(即t)所指节点都应插在q所指节点前,p所指节点后(如果有的话)
  f = f->next;         //在进行插入操作前,先使f后移
  if (q == h) h = t;   //如果当前新链的头节点关键值比f(即t)所指节点关键值小,需要将f(即t)所指节点插在该头节点前,先让新链头节点指针指向
                       //f(即t)所指节点,作为新链的新的头节点
  else  p->next = t;   //否则,将f(即t)所指节点连在p所指节点后
  t->next = q; //不管if还是else,都需要将f(即t)所指节点连在q所指节点前,如果q=NULL,就是让f(即t)所指节点的next域指向NULL,这显然也是正确的
 }
 return h;  //返回新链(排好序的链)的头节点指针
}

struct Student* sort2(struct Student* h)                                                 //选择排序
{                                                                                                             
 struct Student *f=NULL,*t=NULL, *max, *maxbf=NULL, *p;                

 while (h!=NULL)                                                                                   
 {
  for (p = h, max = h; p->next != NULL; p = p->next)
  {
   if (p->next->score > max->score)
   {
    maxbf = p;
    max = p->next;
   }
  }
  if (f==NULL)
  {
   f = max;
   t = max;
  }
  else
  {
   t->next = max;
   t = max;
  }
  if (max==h)
  {
   h = h->next;
  }
  else
  {
   maxbf->next = max->next;
  }
 }
 t->next = NULL;
 return f;
}

struct Student* sort3(struct Student* h)                                            //这是什么排序呢?我也说不好。这是我自己想出来的算                                                                               
{                                                                                                        //法……大体思想是:先从链表第一个结点开始遍历链表,找出关键值(这里是成绩score)最大的(因为
 struct Student *p, *q, *pt=NULL, *pbf=NULL, *qbf=NULL;              //是从大到小排序)结点和链表中第一个结点交换(利用指针实现);然后,从链表中第二个结点开始遍历链
 for (p = h ; p->next!=NULL; pbf = p, p = p->next)                           //表,找出关键值最大的结点和链表中第二个结点交换……如此操作,直到从链表中最后一个结点开始的那趟
 {                                                                                                      //遍历和操作结束
  for (q = p; q->next != NULL;q=q->next)                                         //代码格式很不好,写这段代码时在下还很渣很渣……粘贴到这里时,就更不好看了……对不起大家了
  {

   if (p->score < q->next->score)
   {
    qbf = q; q = q->next;
    if (p==h && p->next==q)
    {
     h = q; p->next = q->next; q->next = p; p = q;
    }
    else
    {
     if (p == h&&p->next != q)
     {
      h = q; pt = q->next; q->next = p->next, qbf->next = p; p->next = pt; p = q; q = qbf;
     }
     else
     {
      if (p != h && p->next == q)
      {
       pt = q->next; pbf->next = q; q->next = p; p->next = pt; p = q;
      }
      else
      {
       if (p != h && p->next != q)
       {
        pt = q->next; pbf->next = q; q->next = p->next; qbf->next = p; p->next = pt; p = q; q = qbf;
       }
      }
     }
    }
   }
  }
 }
 return h;
}


//快排    这里在下也参考了网上的代码,但在下也着实进行了一番改进才编译通过,这里使用了指针的指针,不详细讲了,大家自己分析吧

struct Student* Link_Quick_Sort(struct Student ** head, struct Student ** end)          //  注意这里函数返回值可以写成void,同时将return语句去掉,
{                                                                                       //同时,将main函数中(1)(2)两句改为:
 struct Student * big_head=NULL, *big_end=NULL, *small_head=NULL, *small_end=NULL;   //Link_Quick_Sort(&pt, NULL);
 struct Student * big_tail=NULL, *small_tail = NULL;                                 //for (p=pt, i = 1; i <= n; i++, p = p->next)
 int key = (*head)->score;                              //也是可以的。原因是递归是先进后出,后进先出,二第一次调用时传的是&pt(见main函数中
 struct Student * traversal = (*head)->next;            //第(1)句),故当整个函数结束后,pt的值已修改,且指向排好序的链表的头结点。
 (*head)->next = NULL;                                 
 struct Student *p = NULL;
 while (traversal != NULL)
 {
  if (traversal->score > key)
  {
   if (big_head == NULL) { big_head = traversal; big_tail = traversal; }
   else{ big_tail->next = traversal; big_tail = traversal; }
   traversal = traversal->next;
   big_tail->next = NULL;
  }
  else
  {
   if (small_head == NULL) { small_head = traversal; small_tail = traversal; }
   else{ small_tail->next = traversal; small_tail = traversal; }
   traversal = traversal->next;
   small_tail->next = NULL;
  }
 }
  big_end = big_tail; small_end = small_tail;
  if (big_head != NULL && big_head->next != NULL){ Link_Quick_Sort(&big_head, &big_end); }
  if (small_head != NULL && small_head->next != NULL){ Link_Quick_Sort(&small_head, &small_end); }
  if (big_end != NULL&&small_head != NULL)
  {
   big_end->next = (*head);
   (*head)->next = small_head;
   (*head) = big_head;
   if (end == NULL){ end = &p; }
   (*end) = small_end;
  }
  else if (big_end!=NULL)
  {
   big_end->next = (*head);
   if (end == NULL){  end = &p; }
   (*end) = (*head);
   (*head) = big_head;
  }
  else if (small_head!=NULL)
  {
   (*head)->next = small_head;
   if (end == NULL){ end = &p; }
   (*end) = small_end;
  }
  return (*head);
}

void main()                                                   //用main函数来测试
{
 printf("请依次输入学生的学和姓名\n");
 printf("学号和姓名间以空格隔开\n");
 printf("输入0 0结束\n");
 struct Student* pt,*p;
 struct Student* creat();
 struct Student* sort();               //这里调用的是冒泡排序,要想调用其它排序,在这里改一下函数调用就可以了
 pt=creat();
 int i;
 for ( p=pt,i = 1; i <=n; i++,p=p->next)
  printf("num=%ld score=%d\n", p->num, p->score);
 printf("排序后:\n");
    p=Link_Quick_Sort(&pt, NULL);     //(1)
 for ( i = 1; i <= n; i++, p = p->next)//(2)
  printf("第%d名: num=%ld score=%d\n",i, p->num, p->score);
}

代码已经过测试,在VS2013上成功运行!

发此文有两大目的:

1.和大家交流经验,供需要的人参考。

2.在下菜鸟,代码中难免有不妥之处,恳求大神批评指正。您的批评就是在下提高的起点,对于您的批评,在下将不胜感激!

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