循环链表的基本操作

#include<iostream>
#include<cstdlib>
using namespace std;

struct Node{
    int data;
    Node* next;
};
typedef Node* LinkList;

//函数声明
void show();
void InitList(LinkList &L);
void DestroyList(LinkList &L);
void CreateList(LinkList &L,int length);
void ClearList(LinkList &L);
bool EmptyList(LinkList L);
int LengthList(LinkList L);
int GetElem(LinkList L,int index);
int LocateElem(LinkList L,int e);
bool PriorElem(LinkList L,int cur_e,int &pri_e);
bool NextElem(LinkList L,int cur_e,int &next_e);
bool InsertList(LinkList &L,int index,int value);
bool DeleteList(LinkList &L,int index,int &e);
void Print(LinkList L);

int main(){
    LinkList L;
    int e,index,cur_e,next_e,pri_e,action,length;
    show();
    while(cin>>action){
        switch(action){
            case 1:
                system("cls");
                InitList(L);
                break;
            case 2:
                system("cls");
                cout<<"请输入循环链表中的结点个数:"<<endl;
                cin>>length;
                CreateList(L,length);
                cout<<"创建循环链表成功!"<<endl;
                break;
            case 3:
                system("cls");
                if(EmptyList(L)){
                    cout<<"循环链表为空"<<endl;
                } else {
                    cout<<"循环链表不为空"<<endl;
                }
                break;
            case 4:
                system("cls");
                cout<<"循环链表的长度为:"<<LengthList(L)<<endl;
                break;
            case 5:
                system("cls");
                cout<<"请输入结点的索引"<<endl;
                cin>>index;
                cout<<"第"<<index<<"个结点的值为:"<<GetElem(L,index);
                break;
            case 6:
                system("cls");
                cout<<"请输入结点的值"<<endl;
                cin>>e;
                cout<<e<<"的索引为:"<<LocateElem(L,e);
                break;
            case 7:
                system("cls");
                cout<<"请输入结点的值:"<<endl;
                cin>>e;
                if(PriorElem(L,e,pri_e)){
                    cout<<e<<"的前驱结点的值为:"<<pri_e<<endl<<endl;
                } else {
                    cout<<"循环链表中不包含"<<e<<endl;
                }
                break;
            case 8:
                system("cls");
                cout<<"请输入结点的值:"<<endl;
                cin>>e;
                if(NextElem(L,e,next_e)){
                    cout<<e<<"的后继结点的值为:"<<next_e<<endl<<endl;
                } else {
                    cout<<"循环链表中不包含"<<e<<endl;
                }
                break;
            case 9:
                system("cls");
                cout<<"请输入插入的位置和所插结点的值:"<<endl;
                cin>>index>>e;
                if(InsertList(L,index,e)){
                    cout<<"插入成功"<<endl;
                } else {
                    cout<<"插入失败"<<endl;
                }
                break;
            case 10:
                system("cls");
                ClearList(L);
                cout<<"已清空循环链表"<<endl;
                break;
            case 11:
                system("cls");
                DestroyList(L);
                cout<<"已销毁循环链表"<<endl;
                break;
            case 12:
                system("cls");
                cout<<"请输入将删除的结点的索引"<<endl;
                cin>>index;
                if(DeleteList(L,index,e)){
                    cout<<"第"<<index<<"个元素已经被删除，值为"<<e<<endl<<endl;
                } else{
                    cout<<"删除失败"<<endl;
                }
                break;
            case 13:
                system("cls");
                cout<<"循环链表的各结点为:"<<endl;
                if(!EmptyList(L)){
                    Print(L);
                } else {
                    cout<<"链表为空"<<endl;
                }
                cout<<endl<<endl;
        }
        system("pause");
        system("cls");
        show();
    }
}

void show(){
    cout<<"+------------------------------------------------+"<<endl;
    cout<<"|                                                |"<<endl;
    cout<<"|            1->初始化循环链表                   |"<<endl;
    cout<<"|            2->创建循环链表                     |"<<endl;
    cout<<"|            3->判断链表是否为空                 |"<<endl;
    cout<<"|            4->循环双链表的长度                 |"<<endl;
    cout<<"|            5->获取结点的值                     |"<<endl;
    cout<<"|            6->获取结点的位置                   |"<<endl;
    cout<<"|            7->获取前驱结点                     |"<<endl;
    cout<<"|            8->获取后继结点                     |"<<endl;
    cout<<"|            9->插入结点                         |"<<endl;
    cout<<"|            10->清空循环链表                    |"<<endl;
    cout<<"|            11->销毁循环链表                    |"<<endl;
    cout<<"|            12->删除结点                        |"<<endl;
    cout<<"|            13->打印循环链表                    |"<<endl;
    cout<<"|                                                |"<<endl;
    cout<<"+------------------------------------------------+"<<endl;
}

//初始化循环链表
void InitList(LinkList &L){
    L=new Node;
    if(!L){
        cout<<"初始化失败!"<<endl;
        return;
    }
    L->next=L;
    cout<<"初始化成功!"<<endl;
}

//创建循环链表
void CreateList(LinkList &L,int length){
    LinkList p=L,q;
    for(int i=0;i<length;i++){
        q=new Node;
        cin>>q->data;
        p->next=q;
        p=p->next;
    }
    p->next=L;//注意此时与创建单链表有差异，创建单链表，最后一个结点的指针域为null
    //循环链表的末尾指针域指向头结点
}
//销毁循环链表
void DestroyList(LinkList &L){
    LinkList p,q;
    q=L->next;
    while(q!=L){//没到表尾
        p=q->next;
        delete q;
        q=p;
    }
    delete L;
}

//清空循环链表
void ClearList(LinkList &L){
    LinkList p,q;
    q=L->next;
    while(q!=L){
        p=q->next;
        delete q;
        q=p;
    }
    //前面一部分与销毁表相同，区别在于销毁表会删除头节点，清空表保留头节点，并使头结点的next指向自己
    L->next=L;
    cout<<"已清空循环链表"<<endl;
}

//判断是否为空
bool EmptyList(LinkList L){
    if(L->next==L){
        return true;
    } else {
        return false;
    }
}

//获取长度
int LengthList(LinkList L){
    int i=0;
    LinkList p=L->next;
    while(p!=L){
        i++;
        p=p->next;
    }

    return i;
}

//获取第index个结点的值
int GetElem(LinkList L,int index){
    if(index<0 || index>LengthList(L)){
        cout<<"输入的数值错误"<<endl;
        return 0;
    }
    LinkList p=L->next;
    int j=0;
    while(j<index){
        p=p->next;
        j++;
    }
    return p->data;
}

//获取结点e的位置
int LocateElem(LinkList L,int e){
    LinkList p=L->next;
    int index=1;
    while(p!=L){
        if(e==p->data){
            return index;
        }
        index++;
        p=p->next;
    }
    return 0;
}

//获取当前结点的前一个结点的值
bool PriorElem(LinkList L,int cur_e,int &pri_e){
    //cur_e不为第一个元素
    LinkList p=L->next,q;//p指向第二个元素
    q=p->next;//q指向p的下一个元素
    while(q!=L){
        if(q->data==cur_e){
            pri_e=p->data;
            return true;
        }
        p=q;
        q=q->next;
    }
    return false;
}

//获取当前结点的下一个结点的值
bool NextElem(LinkList L,int cur_e,int &next_e){
    //cur_e不为最后一个元素
    LinkList p=L->next;
    while(p!=L){
        if(p->data==cur_e){
            next_e=p->next->data;
            return true;
        }
        p=p->next;
    }
    return false;
}

//在第index个位置插入结点
bool InsertList(LinkList &L,int index,int value){
    if(index<0 || index>LengthList(L)){
        return false;
    }
    LinkList p=L,q;
    int j=1;
    while(p->next!=L && j<index){
        p=p->next;
        j++;
    }
    q=new Node;
    q->data=value;
    q->next=p->next;
    p->next=q;
    return true;
}

//删除第index个结点
bool DeleteList(LinkList &L,int index,int &e){
    if(index<0 || index>LengthList(L)){
        return false;
    }
    LinkList p=L,q;
    int j=1;
    while(j<index && p->next!=L){
        p=p->next;
        j++;
    }
    q=p->next;
    e=q->data;
    p->next=q->next;
    delete q;
    return true;
}

void Print(LinkList L){
    LinkList p=L->next;
    while(p!=L){
        cout<<p->data<<‘ ‘;
        p=p->next;
    }
}