#ifndef __SCLIST_H__#define __SCLIST_H__#include<cstdio>#include<malloc.h>#include<assert.h>typedef int ElemType;
typedef struct Node {
ElemType data;
struct Node *next;
}
Node,*PNode;
typedef struct List {
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

#include"SClist.h"Node* _buynode(ElemType x) {
Node *s = (Node*)malloc(sizeof(Node));
assert(s != NULL);
s->data = x;
s->next = NULL;
return s;
}
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;
}
void push_back(List *list, ElemType x) {
Node *s = _buynode(x);
list->last->next = s;
list->last = s;
list->last->next = list->first;
list->size++;
}
void push_front(List *list, ElemType x) {
Node *s = _buynode(x);
s->next = list->first->next;
list->first->next = s;
if (list->last == list->first) list->last = s;
list->size++;
}
void show_list(List *list) {
Node *p = list->first->next;
while (p != list->first) {
printf("%d->", p->data);
p = p->next;
}
printf("Nul.n");
}
void pop_back(List *list) {
if (list->size == 0) return;
Node *p = list->first;
while (p->next != list->last) p = p->next;
free(list->last);
list->last = p;
list->last->next = list->first;
list->size--;
}
void pop_front(List *list) {
if (list->size == 0) return;
Node *p = list->first->next;
list->first->next = p->next;
if (list->size == 1) list->last = list->first;
free(p);
list->size--;
}
void insert_val(List *list, ElemType x) {
Node *p = list->first;
while (p->next != list->last && p->next->data < x) p = p->next;
if (p->next == list->last && p->next->data < x) push_back(list, x);
else {
Node *s = _buynode(x);
s->next = p->next;
p->next = s;
list->size++;
}
}
Node* find(List *list, ElemType key) {
if (list->size == 0) return NULL;
Node *p = list->first->next;
while(p != list->first && p->data != key) p = p->next;
if (p == list->first) return NULL;
return p;
}
int length(List *list) {
return list->size;
}
void delete_val(List *list, ElemType x) {
if (list->size == 0) return;
Node *p = find(list, x);
if (p == NULL) {
printf("没有要删除的数据!n");
return;
}
if (p == list->last) pop_back(list);
else {
Node *q = p->next;
p->data = q->data;
p->next = q->next;
free(q);
list->size--;
}
}
void sort(List *list) {
if (list->size == 0 || list->size == 1) return;
Node *s = list->first->next;
Node *q = s->next;
list->last->next = NULL;
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;
}
}
}
void reverse(List *list) {
if (list->size == 0 || list->size == 1) 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;
}
}
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;
}
void destroy(List *list) {
clear(list);
free(list->first);
list->first = list->last = NULL;
}

#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%dn", 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: //destroy(&mylist);
//break;
default: printf("选择错误,请重新选择！n");
break;
}
}
destroy(&mylist);
}