链表—应用实例

链表基本类型结构

基本操作：在指定位置插入节点，删除节点，添加节点

 

template <class T> class list
{
public:
    list();
    ~list();
    void insert(list_node<T> *,const T &);
    void deletenode(list_node<T> *);
    void addnode(const T &);
    void print();
private:
    list_node<T> *head;
    list_node<T> *rear;
};

template <class T> list<T>::list()
{
    head=new list_node<T>();
    if (head==NULL)
        cerr<<"new error"<<endl;
    head->next=NULL;
    rear=head;
}

template<class T> void  list<T>::addnode(const T &value)
{
    list_node<T>* p=new list_node<T>();
    p->value=value;
    p->next=NULL;
    rear->next=p;
    rear=p;
}

template<class T>void list<T>::insert(list_node<T> *pos,const T &value)
{
    list_node<T>* p=new list_node<T>;
    list_node<T>*q=p->next
    p->value=value;
    p->next=pos->next;
    pos->next=p;
}

template<class T> void list<T>::deletenode(list_node<T> *pos)
{
    list_node<T> *p=head->next;
    while (p->next!=pos&&p->next!=NULL)
    {
        p=p->next;
    }
    if (p->next==NULL)
    {
        cout<<"count find postion"<<endl;
    }

    p->next=pos->next;
    delete pos;

}
template <class T> list<T>::~list()
{
    list_node<T> *p=head,*q=NULL;
    while (p)
    {
        q=p->next;
        delete p;
        p=q;
    }
}

template<class T> void list<T>::print()
{
    list_node<T> *p=head->next;
    while (p)
    {
        cout<<p->value<<endl;
        p=p->next;
    }
}

 

1.链表实现多项式加法

如：a=3x^14+2x^8+1 b=8x^14-3x^10+10x^6

多项式链式存储：

struct poly_node{
 int coef;    //系数
 int expen;  //指数
 poly_node *next;
};

poly_node * poly_add(poly_node *a,poly_node *b)
{
    poly_node *ap=a,*bp=b;
    poly_node *cp=NULL;
    poly_node *c=NULL;
    poly_node *p=NULL;
    poly_node *left=NULL;

    while (ap!=NULL&&bp!=NULL)
    {
        p=(poly_node *)malloc(sizeof(poly_node));
        
        if(ap->expen==bp->expen)
        {
            p->coef=ap->coef+bp->coef;
            p->expen=ap->expen;
            p->next=NULL;
            ap=ap->next;
            bp=bp->next;
        }
        else if (ap->expen>bp->expen)
        {
            p->coef=ap->coef;
            p->expen=ap->expen;
            p->next=NULL;
            ap=ap->next;
        }
        else
        {
            p->coef=bp->coef;
            p->expen=bp->expen;
            p->next=NULL;
            bp=bp->next;
        }
        if(cp==NULL)
        {
            cp=p;
            c=cp;
        }
        else
        {
            cp->next=p;
            cp=p;
        }

    }
    if(ap==NULL&&bp!=NULL)
    {
        left=bp;
    }
    else if (ap!=NULL&&bp==NULL)
    {
        left=ap;
    }
    else
        left=NULL;
    while (left)
    {
        p=new poly_node;
        p->coef=left->coef;
        p->expen=left->expen;
        p->next=NULL;
        cp->next=p;
        cp=cp->next;
        left=left->next;
    }

    return c;
}

//将一个字符串表示的多项式转化链表形式
poly_node * str2node(const char * str)
{
    poly_node * start=NULL;
    const char * p=str,*q=NULL;
    poly_node *newnode;
    poly_node *rear=NULL;;
    int value=0;
    int exp=0;
    int flag=1;

    while (*p)
    {
        value=0;
        exp=0;
        flag=1;
        if (isdigit(*p))
        {
            q=p;
            flag=1;
        }
        else if(*p=='-')
        {
            flag=-1;
            q=p+1;
            value=0;
        }
        else if (*p=='+')
        {
            flag=1;
            q=p+1;
            value=0;
        }else
        {
            value=1;
            flag=1;
        }
    
        while (*q!='x'&&*q!='X')
        {
            value=value*10+*q-48;
            q++;
        }
        
        value=value*flag;
        q++;
        if(*q=='-')
        {
            flag=-1;
            q++;
        }else
        {
            flag=1;
        }
        while (*q!='\0'&&*q!='+'&&*q!='-')
        {
            exp=exp*10+*q-48;
            q++;
        }
        exp=exp*flag;

        newnode=new poly_node;
        newnode->coef=value;
        newnode->expen=exp;
        newnode->next=NULL;
        if(start==NULL)
        {
            start=newnode;
            rear=newnode;
        }
        else
        {
            rear->next=newnode;
            rear=newnode;
        }
        p=q;
    }

    return start;
}

//将链表转化为字符串形式
void  node2str(poly_node *start,char *str)
{
    poly_node *p=start;
    char temp[64];

    while (p)
    {
        sprintf(temp,"%+dx%d",p->coef,p->expen);
        strcat(str,temp);
        p=p->next;
    }

}