循环链表（尾指针）

//循环链表（尾指针）
#include <stdio.h>
#include <stdlib.h>

#define OK 1
#define TRUE 1
#define FLASE 0
#define ERROR 0

typedef struct elem {
  int n;
}elem;  //定义元素

typedef struct splist {
  elem data;
  splist* nest;
}splist,*list;

//创建并初始化链表
int InitList(list &L) {
  L = (list)malloc(sizeof(splist));
  if (L == NULL) return ERROR;
  L->data.n = 0;
  L->nest = L;
  return OK;
}

//建立链表并添加元素
int CreateList(list &L) {
  L = (list)malloc(sizeof(splist));
  if (L == NULL) return ERROR;
  L->nest = L;
  list p;
  int n = 0, m = 0;
  printf("请输入要加入的元素个数:");
  scanf("%d", &n);
  while (n--) {
    p = (list)malloc(sizeof(splist));
    scanf("%d", &m);
    p->nest = L->nest;
    L->nest = p;
    L = p;
    p->data.n = m;
  }
  return OK;
}

//加入一个元素
int AddList(list &L,int i,int n){
  if (i <= 0) return ERROR;
  int j = 0;
  list p = L->nest;
  while(j<i-1 && p!=L) {
    p = p->nest;
    j++;
  }
  if (j < i-1) return ERROR;
  list s = (list)malloc(sizeof(splist));
  s->data.n = n;
  s->nest = p->nest;
  p->nest = s;
  if (p == L) L = s;
  return OK;
}

//删除一个结点
int DeleteList(list &L, int i) {
  if (i <= 0) return ERROR;
  int j = 0;
  list p = L->nest;
  while (j < i-1 && p->nest != L) {
    p = p->nest;
    j++;
  }
  if (j < i - 1) return ERROR;
  list q = p->nest;
  p->nest = q->nest;
  if (q == L) L = p;
  free(q);
  return OK;
}

//求链表长度并返回元素个数
int LengthList(list &L) {
  int i = 0;
  list p = L->nest;
  while (p != L) {
    p = p->nest;
    i++;
  }
  return i;
}

//判断链表是否为空
int EmptyList(list &L) {
  if (L->nest == L) return TRUE;
  return FLASE;
}

//将第i个结点的元素存到e中
int SearchList(list &L,int i, elem* e) {
  if (i <= 0) return ERROR;
  int j = 0;
  list p = L->nest;
  while (j < i && p != L) {
    p = p->nest;
    j++;
  }
  if (j < i) return ERROR;
  e->n = p->data.n;
  return OK;
}

//清空链表
int ClearList(list &L) {
  list s = L->nest;//保留头结点
  list p = L->nest->nest,q;
  while (s->nest != s) {
    q = p->nest;
    L->nest->nest = q;
    free(p);
    p = q;
  }
  L = s;
  return OK;
}

//销毁链表
int DestoryList(list &L) {
  list s = L->nest;//保留头结点
  list p = L->nest->nest, q;
  while (s->nest != s) {
    q = p->nest;
    L->nest->nest = q;
    free(p);
    p = q;
  }
  L = s;
  free(L);
  return OK;
}

//将b连接在a的后面并释放b,直接在a上做改变
int ContactList(list &a, list &b) {
  list s1 = b->nest, s2 = a->nest;//保留b和a的头结点
  list p = b->nest->nest;
  list q = NULL;
  while (s1->nest != s1) {
    q = p->nest;
    a->nest = p;
    p->nest = s2;
    a = p;
    s1->nest = q;
    p = q;
  }
  b = NULL;
  free(s1);
  return OK;
}

int main()
{
  return 0;
}