C语言实现单向链表及其各种排序

时间:2022-11-22 10:19:55

  #include

  #include

  #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);

  }文章来源:http://www.mfqyw.com/