建立一个带附加头结点的单链表.实现测长/打印/删除结点/插入结点/逆置/查找中间节点/查找倒数第k个节点/判断是否有环

// 建立一个带附加头结点的单链表/测长/打印
#include<iostream>
using namespace std;

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

LinkList *creat()
{
LinkList *head,*p,*s;
int x;
head=new LinkList[sizeof(LinkList)];
head->data=0;
p=head;
while(1)
{
cout<<"Please input the data:"<<endl;
cin>>x;

if(x==0) break;

s=new LinkList[sizeof(LinkList)];
s->data=x;
p->next=s;
p=s;
}
p->next=NULL;
return head;
}

int length(LinkList *head)
{
int n=0;
LinkList *p;
p=head->next;
while(p!=NULL)
{
p=p->next;
n++;
}
return n;
}

void print(LinkList *head)
{
LinkList*p;
p=head->next;
while(p!=NULL)
{
cout<<p->data<<" ";
p=p->next;
}
cout<<endl;
}

/*LinkList *del(LinkList *head,int deldata)
{
LinkList *p1,*p2;
p1=head;
while(deldata != p1->data && p1->next != NULL)
{
p2=p1;
p1=p1->next;
}
if(deldata==p1->data)
{
if(p1==head)
{
head=p1->next;
free(p1);
}
else
p2->next=p1->next;
}
else
cout<<deldata<<"could not been found"<<endl;
return head;
}*/
LinkList *del(LinkList *head,int deldata)
{
LinkList *p1,*p2;
p1=head;
while(p1->next !=NULL)
{
p2=p1;
p1=p1->next;
if(deldata==p1->data)
{
p2->next=p1->next;
break;
}
}
if(p1->next ==NULL)
cout<<deldata<<" could not been found"<<endl;
return head;
}

LinkList *insert(LinkList *head,int num)
{
LinkList *p0,*p1,*p2;
p1=head;
p0=new LinkList[sizeof(LinkList)];
p0->data=num;
while(p1->next != NULL)
{
p2=p1;
p1=p1->next;
if(p0->data<p1->data)
{
p2->next=p0;
p0->next=p1;
break;
}
if(p0->data==p1->data)
{
cout<<"yao cha ru de yuan su yi jing cun zai"<<endl;
break;
}
}
if(p0->data>p1->data)
{
p1->next=p0;
p0->next=NULL;
}

return head;
}

LinkList *Reverse(LinkList *head)
{
LinkList *p1,*p2,*p3;
if(head==NULL||head->next==NULL)
return head;
p1=head;
p2=p1->next;
p3=p2->next;
p1->next=NULL;
while(p3)
{
p2->next=p1;
p1=p2;
p2=p3;
p3=p3->next;
}
p2->next=p1;
head=p2;
return head;

}

LinkList* searchmid(LinkList* head)
{
LinkList* mid=new LinkList[sizeof(LinkList)];
LinkList *p1=head->next;
LinkList *p2=p1;

while(p1->next != NULL && p1->next->next != NULL )
{
p1=p1->next->next;
p2=p2->next;

}
mid=p2;
return mid;
}

LinkList* finddaoshuk(LinkList* head,int k)
{
LinkList *p1=head->next;
LinkList *p2=p1;
for(int i=1;i<k;i++)
{
if(p1->next!=NULL)
p1=p1->next;
else return NULL;
}
while(p1->next!=NULL)
{
p1=p1->next;
p2=p2->next;
}
return p2;
}

bool IsCircle(LinkList* head)
{
LinkList *p1=head->next;
LinkList *p2=p1;
while(p1->next != NULL && p1->next->next != NULL )
{
p1=p1->next->next;
p2=p2->next;
if(p2==p1) return true;
}
return false;
}

int main()
{
LinkList*node=creat();
//cout<<length(node)<<endl;
print(node);
bool IsCir=IsCircle(node);
if(IsCir==true) cout<<"The list has circle"<<endl;
else cout<<"The list has not circle"<<endl;

/*LinkList* mid=searchmid(node);
cout<<mid->data<<endl;
cout<<"Please output dao shu di k ge jie dian"<<endl;
int k=2;
LinkList* pk=finddaoshuk(node,k);
if(pk==NULL) cout<<k<<" k is biger than the lengh of node";
else cout<<pk->data<<endl;*/

/* LinkList*afterdel=del(node,3);
print(afterdel);
LinkList*afterinsert=insert(node,10);
print(afterinsert);

cout<<"after reverse LinkList"<<endl;
LinkList*afterreverse=Reverse(afterinsert);
print(afterreverse);*/

return 0;
}