链表4-循环链表

循环链表的特点: 链表的尾结点后继指向头结点

循环链表的结构

typedef struct Node{
    int data; //数据域
    struct Node *nextNode; //后继
} Node;

循环链表的初始化

Node* initHeader(){
    //创建头结点
    Node *header = (Node*)malloc(sizeof(Node));
    //头结点的数据(用于存储链表长度)
    header->data = 0;
    //头结点的后继
    header->nextNode = header;
    //返回
    return header;
}

后插法添加元素

//后插法添加元素(返回尾结点)
Node* addNode(Node *header, Node *roar){
    //空链表
    if(!header){
        cout << "链表不存在!" << endl;
        return NULL;
    }
    //开辟空间
    Node *newNode = (Node*)malloc(sizeof(Node));
    //赋值 
    cout << "输入值" << endl;
    cin >> newNode->data;
    newNode->nextNode = NULL;
    //尾结点后继指向新结点
    roar->nextNode = newNode;
    //新结点后继指向header
    newNode->nextNode = header;
    //更新链表长度
    header->data++;
    //更新尾结点
    return newNode;
}

链表长度

void sizeOfLinkList(Node *header){
    //空链表
    if(!header){
        cout << "链表不存在!" << endl;
        return;
    }  
    cout << "链表长度: " << header->data << endl;
}

输出链表

void display(Node *header){
    //空链表
    if(!header){
        cout << "链表不存在!" << endl;
        return;
    }    
    Node *curNode = header->nextNode;
    while(curNode!=header){
        cout << curNode->data << " ";
        //前进
        curNode = curNode->nextNode;
    }
    cout << endl;
}

测试

int main(){
    int choice;
    Node *header=NULL;
    Node *roar=NULL;
    int length=0;

    do{
        cout << "--------------" << endl;
        cout << "1.创建" << endl;
        cout << "2.在尾部插入新节点" << endl;
        cout << "3.输出链表" << endl;
        cout << "0.退出" << endl;
        cout << "输入选项:";
        cin >> choice;
        switch(choice){
            case 1:
                header = initHeader();
                roar = header;
                break;
            case 2:
                roar = addNode(header, roar, length);
                break;
            case 3:
                display(header);
                break;
            default:
                break;
        }
    }while(choice!=0);

    system("pause");
    return 0;
}