链表习题

链表习题：

1. 单链表反转

2. 链表中环的检测

3. 两个有序的链表合并

4. 删除链表倒数第 n 个结点

5. 求链表的中间结点

#include <iostream>
using namespace std;

typedef struct LNode
{
    int data;
    struct LNode *next;
}LNode,*Linklist;

//输出链表
void Printf_LNode(Linklist L)
{
    LNode *p = L->next;
    while(p)
    {
        if(!p->next)
        {
            cout<<p->data;
        }
        else cout<<p->data<<"->";
        p = p->next;
    }
    cout<<endl;
}

//带环链表输出方式
void PrintfCircleLinklist(Linklist L)
{
    int number = 0;
    LNode *q = L->next;
    while(q)
    {
        if(number == 9)
        {
            cout<<q->data;
            break;
        }
        cout<<q->data<<"->";
        number++;
        q = q->next;
    }
    cout<<endl;
}
//后插法创建链表
Linklist CreatLinkList()
{

    int n;
    cout<<"请输入节点个数:"<<endl;
    cin>>n;
    Linklist L = new LNode;
    L->next=nullptr;
    LNode *r = L;
    cout<<"请输入节点内容:"<<endl;
    for(int i = 0;i < n;i++)
    {
        LNode *p = new LNode;
        p->next = nullptr;
        r->next = p;
        r = p;
        cin>>p->data;
    }
    return L;
}

//单链表反转
void Reversal(Linklist L)
{
    cout<<"反转之前链表内容是:";
    Printf_LNode(L);
    Linklist LR;
    LR = new LNode;
    LR->next = nullptr;
    LNode *p = L->next;
    while(p)
    {
        LNode *s = new LNode;
        s->next = LR->next;
        s->data = p->data;
        LR->next = s;
        p = p->next;
    }
    cout<<"反转之后链表内容是:";
    Printf_LNode(LR);
}

//创建一个带环的链表
Linklist CrearCircleLinklist()
{
    Linklist L;
    L = new LNode;
    L->next = nullptr;
    LNode *r = L;
    LNode *c;
    for(int i = 0; i < 6;i++)
    {
        LNode *p = new LNode;
        p->next = nullptr;
        r->next = p;
        p->data = i;
        r = p;
        if(i == 4)
        {
            c = r;
        }
    }
    r->next = c;
    return L;
}
//链表中环的检测
bool HasCircle(Linklist L)
{
    cout<<"检测链表内容为:";
    LNode *pslow = L->next;
    LNode *pfast =pslow->next;
    for(;pslow&&pfast;pslow = pslow->next,pfast = pfast->next->next)
    {
        if(pslow == pfast)
        {
            PrintfCircleLinklist(L);
            cout<<"检测结果:链表带环"<<endl;
            return true;
        }
    }
    Printf_LNode(L);
    cout<<"检测结果:链表不带环"<<endl;
    return false;
}

//链表合并
Linklist MergeLinklist()
{
    cout<<"合并链表，先创建两个链表"<<endl;
    Linklist L1,L2,L3;
    L1 = CreatLinkList();
    L2 = CreatLinkList();
    L1 = L1->next;
    L2 = L2->next;
    L3 = new LNode;
    L3->next = nullptr;
    LNode *p = L3;
    if(L1 == nullptr && L2 == nullptr)
    {
        return nullptr;
    }
    else if(L1 == nullptr && L2 != nullptr)
    {
        return L2;
    }
    else if(L1 != nullptr && L2 == nullptr)
    {
        return L1;
    }
    else
    {
        while(L1 && L2)
        {
            if(L1->data <= L2->data)
            {
                p->next = L1;
                L1 = L1->next;
            }
            else
            {
                p->next = L2;
                L2 = L2->next;
            }
            p = p->next;
        }
    }
    p->next = L1 == nullptr ? L2 : L1;
    return L3;
}
//求链表长度
int LinklistLength(Linklist L)
{
    int length = 0;
    LNode *p = L->next;
    while(p)
    {
        length++;
        p = p->next;
    }
    return length;
}
//删除节点
void DeleteLNode()
{
    int pos;
    Linklist L = CreatLinkList();
    LNode *p = L;
    cout<<"链表内容是:";
    Printf_LNode(L);
    cout<<"请输入你要删除倒数第几个节点:";
    cin>>pos;
    if(pos > LinklistLength(L))
    {
        cout<<"你要删除的节点不存在"<<endl;
        return;
    }
    else if(pos == LinklistLength(L))
    {
        p->next = p->next->next;
    }
    else
    {
        for(int i = 0;i < (LinklistLength(L)- pos);i++,p = p->next);
        p->next = p->next->next;
    }
    cout<<"删除之后链表内容是:";
    Printf_LNode(L);
}
//寻找中间节点
void MiddleLNode()
{
    Linklist L = CreatLinkList();
    LNode *p = L->next;
    cout<<"链表内容是:";
    Printf_LNode(L);
    if(LinklistLength(L) % 2 == 1)
    {
        for(int i = 0;i < LinklistLength(L)/2;i++,p = p->next);
        cout<<"链表中间节点是:"<<p->data<<endl;
    }
    else
    {
        for(int i = 0; i < LinklistLength(L)/2-1;i++,p = p->next);
        cout<<"链表中间节点是:"<<p->data<<"和"<<p->next->data<<endl;
    }
}
int main()
{
    cout<<"--------------------------------------------"<<endl;
    cout<<"1.链表反转"<<endl;
    Linklist L = CreatLinkList();
    Reversal(L);
    cout<<"-------------------分界线-------------------"<<endl;
    cout<<"2.链表中环的检测"<<endl;
    HasCircle(L);
    HasCircle(CrearCircleLinklist());
    cout<<"-------------------分界线-------------------"<<endl;
    cout<<"3.两个有序链表的合并:"<<endl;
    Linklist SumLinklist = MergeLinklist();
    cout<<"链表合并之后的内容是:"<<endl;
    Printf_LNode(SumLinklist);
    cout<<"-------------------分界线-------------------"<<endl;
    cout<<"4.删除链表倒数第n个节点"<<endl;
    DeleteLNode();
    cout<<"-------------------分界线-------------------"<<endl;
    cout<<"5. 求链表的中间结点"<<endl;
    MiddleLNode();
    return 0;
}