循环单链表实现
/********************************************************
* SClist.h头文件
/********************************************************/
#ifndef __SCLIST_H__
#define __SCLIST_H__
#include<stdio.h>
#include<malloc.h>
#include<assert.h>
typedef int ElemType;
typedef struct Node { //定义结构体
ElemType data;
struct Node *next;
}Node,*PNode;
typedef struct List { //定义头尾节点及链表长度
PNode first;
PNode last;
size_t size;
}List;
void InitSClist(List *list);//初始化循环单链表
void push_back(List *list, ElemType x);//在循环单链表的末尾插入元素
void push_front(List *list, ElemType x);//在循环单链表的头部插入元素
void show_list(List *list);//打印循环单链表
void pop_back(List *list);//删除循环单链表的最后一个元素
void pop_front(List *list);//删除循环单链表的第一个元素
void insert_val(List *list, ElemType val);//将数据元素插入到循环单链表中（要求此时循环单链表中的数据元素顺序排列）
Node* find(List *list, ElemType x);//查找循环单链表中数据值为x的结点
int length(List *list);//求循环单链表的长度
void delete_val(List *list, ElemType x);//按值删除循环单链表中的某个数据元素
void sort(List *list);//对循环单链表进行排序
void reverse(List *list);//逆置循环单链表
void clear(List *list);//清除循环单链表
void destroy(List *list);//摧毁循环单链表
//优化
Node* _buynode(ElemType x);//创建结点
#endif
/********************************************************
* SClist.c文件
/********************************************************/
#include"SClist.h"
/* 创建新节点 */
Node* _buynode(ElemType x) {
Node *s = (Node*)malloc(sizeof(Node));
assert(s != NULL);
s->data = x;
s->next = NULL;
return s;
}
/* 初始化链表 */
void InitSClist(List *list) {
Node *s = (Node*)malloc(sizeof(Node));
assert(s != NULL);
list->first = list->last = s;
list->last->next = list->first;//让链表最后一个结点的指针域指向头结点，从而时链表循环
list->size = 0;
}
/* 尾部插入元素 */
void push_back(List *list, ElemType x) {
Node *s = _buynode(x);
list->last->next = s; //尾插
list->last = s; //赋地址
list->last->next = list->first;
list->size++;
}
/* 头部插入元素 */
void push_front(List *list, ElemType x) {
Node *s = _buynode(x);
s->next = list->first->next; //头插
list->first->next = s;
if (list->last == list->first)
list->last = s;
list->size++;
}
/* 打印链表 */
void show_list(List *list) {
Node *p = list->first->next;
while (p != list->first) {
printf("%d->", p->data);
p = p->next;
}
printf("Nul.\n");
}
/* 尾部释放一个元素 */
void pop_back(List *list) {
if (list->size == 0)
return;
Node *p = list->first;
while (p->next != list->last)
p = p->next; //找到尾部节点的上一个节点
free(list->last); //释放尾部元素
list->last = p; //p节点赋给尾部节点
list->last->next = list->first; //再使链表指向头节点
list->size--;
}
/* 从头释放一个元素 */
void pop_front(List *list) {
if (list->size == 0)
return;
Node *p = list->first->next;
list->first->next = p->next;
if (list->size == 1) //判断表中是否只有一个元素
list->last = list->first;
free(p);
list->size--;
}
/* 由小到大插入元素 */
void insert_val(List *list, ElemType x) {
Node *p = list->first;
while (p->next != list->last && p->next->data < x) //轮询找出大于X的元素并在前面插入
p = p->next;
if (p->next == list->last && p->next->data < x) //只有一个元素
push_back(list, x);
else { //没有元素
Node *s = _buynode(x);
s->next = p->next;
p->next = s;
list->size++;
}
}
/* 查找链表元素 */
Node* find(List *list, ElemType key) {
if (list->size == 0) //链表不存在
return NULL;
if (p == list->first) //链表为空
return NULL;
Node *p = list->first->next;
while(p != list->first && p->data != key)
p = p->next;
return p;
}
/* 链表长度 */
int length(List *list) {
return list->size;
}
/* 删除链表元素 */
void delete_val(List *list, ElemType x) {
if (p == NULL) {
return;
}
if (list->size == 0)
return;
Node *p = find(list, x); //找出元素
if (p == list->last) //p为尾节点
pop_back(list);
else { //p不为尾节点，删除p
Node *q = p->next;
p->next = q->next;
free(q);
list->size--;
}
}
/* 对循环单链表进行排序 */--------------？
void sort(List *list) {
if (list->size == 0 || list->size == 1) //链表长度为0或1不排序
return;
Node *s = list->first->next; //第一个元素节点
Node *q = s->next; //第二个元素节点
list->last->next = NULL; //断开链表连接
list->last = s;
list->last->next = list->first;
while (q != NULL) {
s = q;
q = q->next;
Node *p = list->first;
while (p->next != list->last && p->next->data < s->data)
p = p->next;
if (p->next == list->last &&p->next->data < s->data) {
list->last->next = s;
list->last = s;
list->last->next = list->first;
}
else {
s->next = p->next;
p->next = s;
}
}
}
/* 链表逆序 */ ---------------->
void reverse(List *list) {
if (list->size == 0 || list->size == 1) //没有元素或单个元素则忽略
return;
Node *p = list->first->next;
Node *q = p->next;
list->last->next = NULL;
list->last = p;
list->last->next = list->first;
while (q != NULL) {
p = q;
q = q->next;
p->next = list->first->next;
list->first->next = p;
}
}
/* 释放链表所有元素 */
void clear(List *list) {
Node *p = list->first->next;
while (p != list->first) {
list->first->next = p->next;
free(p);
p = list->first->next;
}
list->last = list->first;
list->last->next = list->first;
list->size = 0;
}
/* 摧毁链表 */
void destroy(List *list) {
clear(list);
free(list->first);
list->first = list->last = NULL;
}
/********************************************************
* main函数
/********************************************************/
#include"SClist.h"
void main() {
List mylist;
InitSClist(&mylist);
ElemType item;
Node *p = NULL;
int select = 1;
while (select) {
printf("*******************************************\n");
printf("*[1] push_back [2] push_front *\n");
printf("*[3] show_list [4] pop_back *\n");
printf("*[5] pop_front [6] insert_val *\n");
printf("*[7] find [8] length *\n");
printf("*[9] delete_val [10] sort *\n");
printf("*[11] reverse [12] clear *\n");
printf("*[13*] destroy [0] quit_system *\n");
printf("*******************************************\n");
printf("请选择：>>");
scanf("%d", &select);
if (select == 0) break;
switch (select) {
case 1:
printf("请输入要插入的数据（-1结束）:>");
while ( scanf("%d", &item) && （ item != -1) ）{
push_back(&mylist, item);
}
break;
case 2:
printf("请输入要插入的数据（-1结束）:>");
while ( scanf("%d", &item) && （ item != -1) ）{
push_front(&mylist, item);
}
break;
case 3:
show_list(&mylist);
break;
case 4:
pop_back(&mylist);
break;
case 5:
pop_front(&mylist);
break;
case 6:
printf("请输入要插入的数据:>");
scanf("%d", &item);
insert_val(&mylist, item);
break;
case 7:
printf("请输入要查找的数据:>");
scanf("%d", &item);
p = find(&mylist, item);
if (p == NULL)
printf("要查找的数据在单链表中不存在！\n");
break;
case 8:
printf("单链表的长度为%d\n", length(&mylist));
break;
case 9:
printf("请输入要删除的值:>");
scanf("%d", &item);
delete_val(&mylist, item);
break;
case 10:
sort(&mylist);
break;
case 11:
reverse(&mylist);
break;
case 12:
clear(&mylist);
break;
//case 13: //推出再释放
//destroy(&mylist);
//break;
default:
printf("选择错误,请重新选择！\n");
break;
}
}
destroy(&mylist);
}
