单向循环链表

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单向循环链表是在单向链表的基础上，将尾结点的指针指向首元结点。

1、单向循环链表的创建

Status initList(LinkList *L,ElemType data){
    *L = (LinkList)malloc(sizeof(Node));
    if (*L==NULL) return ERROR;
    
    (*L)->data = data;
    (*L)->next = (*L);
    return OK;
}

2、单向循环链表插入数据

Status insertList(LinkList *L, int i, ElemType data){
    if (*L == NULL) return ERROR;
    
    LinkList temp = (LinkList)malloc(sizeof(Node));
    if (temp == NULL) return ERROR;
    temp->data = data;
    
    LinkList target;
    if (i == 1) {
        for (target = *L; target->next != *L; target = target->next);
        target->next = temp;
        temp->next = *L;
        *L = temp;
    }else{
        int j;
        for (j = 1, target = *L; target->next != *L && j<i-1; j++,target = target->next);
        temp->next = target->next;
        target->next = temp;
    }
    return OK;
}

3、单向循环链表删除元素

Status deleteList(LinkList *L, int i){
    if (*L == NULL)  return ERROR;
    
    if ((*L)->next == *L) {
        *L = NULL;
        free(*L);
        return OK;
    }
    LinkList temp, target;
    if (i == 1) {
        temp = *L;
        for (target = *L; target->next != *L; target = target->next);
        target->next = temp->next;
        *L = target->next;
        free(temp);
    }else{
        int j;
        for (j = 1, target = *L; target->next != *L && j<i-1; j++,target = target->next);
        
        if (target->next == *L) {
            return ERROR;
        }
        temp = target->next;
        target->next = temp->next;
        free(temp);
    }
    return OK;
}

4、单向循环链表查询值

int searchValue(LinkList L, int value){
    LinkList temp = L;
    int i = 1;
    
    while (temp->next != L && temp->data != value) {
        i++;
        temp = temp->next;
    }
    if (temp->next == L && temp->data != value) {
        return -1;
    }
    return i;
}

5、遍历单向循环链表

void display(LinkList L){
    if (L==NULL) {
        printf("打印的链表为空!\n");
        return;
    }else{
        printf("链表数据为：");
        LinkList temp = L;
        do{
            printf("%5d",temp->data);
            temp = temp->next;
        }while (temp != L);
        printf("\n");
    }
}