日常编程练习(二)

1、从头到尾打印链表

首先创建单链表,定义一个尾插入和删除操作:

struct Listnode
{
    int m_nKey;
    Listnode *next;
};

void init_List(Listnode **head)
{
    *head=new Listnode;
    if(*head==NULL)
        return;
    (*head)->next=NULL;
    (*head)->m_nKey=0;
}

void add_node(Listnode** head,int val)
{
    Listnode* node=new Listnode;
    if(node==NULL)
        return;
    node->m_nKey=val;
    node->next=NULL;

    if((*head)->next==NULL)
        (*head)->next=node;
    else
    {
        Listnode* temp=(*head)->next;
        while(temp->next!=NULL)
            temp=temp->next;
        temp->next=node;
    }
}

void delete_node(Listnode** head,int val)
{
    Listnode* temp=(*head)->next;
    Listnode* before_temp=*head;
    if((*head)->next==NULL)
        return;
    else
    {
        while(temp->m_nKey!=val&&temp->next!=NULL)
        {
            before_temp=temp;
            temp=temp->next;
        }
        if(temp!=NULL&&temp->m_nKey==val)
        {
            before_temp->next=temp->next;
            delete(temp);
        }

    }
}

两种方法可以实现从尾到头打印,一种是栈,另一种是递归:

vector<int> rprint1(Listnode* head)    //栈实现
{
    vector<int> print_data;
    stack<Listnode*> s_node;
    Listnode* node=head;
    while(node!=NULL)
    {
        s_node.push(node);
        node=node->next;
    }
    while(!s_node.empty())
    {
        print_data.push_back(s_node.top()->m_nKey);
        s_node.pop();
    }
    return print_data;
}

void rprint2(Listnode* head)     //递归实现
{
    if(head!=NULL)
    {
        if(head->next!=NULL)
            rprint2(head->next);
        cout<<head->m_nKey<<" ";
    }
}

二、删除从栈尾部开始算的第n个节点

可是使用双指针控制距离,实现定位

void delete_r_n_node(Listnode *head,int n) //n指从尾部开始数的位数加1
{
    Listnode* r1=head;
    Listnode* r2=head;
    Listnode* temp;
    while(n)
    {
        if(r1->next!=NULL)
            r1=r1->next;
        else
            return;
        n--;
    }
    while(r1->next!=NULL)
    {
        temp=r2;
        r1=r1->next;
        r2=r2->next;
    }
    if(r2->next!=NULL)
    {
        temp->next=r2->next;
        delete r2;
    }
}

三、在O(1)时间内删除链表结点

void DeleteNode(Listnode **head,Listnode* Pdeleted)
{
    if(*head==NULL)
        return;
    //当删除结点不是尾结点
    if(Pdeleted->next!=NULL)
    {
       Listnode* temp=Pdeleted->next;
       Pdeleted->m_nKey=Pdeleted->next->m_nKey;
       Pdeleted->next=Pdeleted->next->next;
       delete temp; 
       temp=NULL;
    }
    //当删除节点是尾结点
    else if((*head)->next==Pdeleted)
    {
        delete Pdeleted;
        Pdeleted=NULL;
        (*head)->next=NULL;
    }
    else
    {
        Listnode* temp=*head;
        while(temp->next!=Pdeleted)
            temp=temp->next;
        if(temp->next==Pdeleted)
        {
            temp->next=NULL;
            delete Pdeleted;
            Pdeleted=NULL;
        }
    }    
}

四、反转链表

Listnode* ReverseList1(Listnode* head)
{
    Listnode* rev=NULL;
    //头结点为空
    if(head==NULL)
        return NULL;
    Listnode* temp=head;
    Listnode* pPrew=NULL;
    while(temp!=NULL)
    {
        Listnode* pnext=temp->next;
        if(pnext==NULL)
            rev=temp;
        temp->next=pPrew;
        pPrew=temp;
        temp=pnext;
    }
    return rev;
}

Listnode* ReverseList2(Listnode* head)
{
    if(head==NULL||head->next==NULL)
        return head;
    else
    {
        Listnode* newlist=ReverseList2(head->next);
        head->next->next=head;
        head->next=NULL;
        return newlist;
    }
}

五、合并两个排好序的链表

//递归实现
Listnode* mergeList1(Listnode* L1,Listnode* L2)
{
    //当存在空指针时
    if(L1==NULL)
        return L2;
    else if(L2==NULL)
        return L1;
    Listnode *merge_node=NULL;
    if(L1->m_nKey>=L2->m_nKey)
    {
        merge_node=L2;
        merge_node->next=mergeList1(L1,L2->next);
    }
    else
    {
        merge_node=L1;
        merge_node->next=mergeList1(L1->next,L2);
    }
    return merge_node;
}

//迭代循环实现
Listnode* mergeList2(Listnode* L1,Listnode* L2)
{
    if(L1==NULL)
        return L2;
    else if(L2==NULL)
        return L1;
    Listnode* merge_node=NULL;
    Listnode* node=NULL;
    if(L1->m_nKey<=L2->m_nKey)
    {
        node=L1;
        L1=L1->next;
    }
    else
    {
        node->next=L2;
        L2=L2->next;
    }
    merge_node=node;     //获取头指针
    while(L1!=NULL&&L2!=NULL)
    {
        if(L1->m_nKey<=L2->m_nKey)
        {
            node->next=L1;
            node=L1;
            L1=L1->next;
        }
        else
        {
            node->next=L2;
            node=L2;
            L2=L2->next;
        }
    }
    if(L1!=NULL)
        node->next=L1;
    else
        node->next=L2;
    return merge_node;
}

六、寻找两个链表的第一个公共结点

Listnode* FindFirstCommonNode(Listnode* L1,Listnode* L2)
{
    int L1_length=getlengthlist(L1);
    int L2_length=getlengthlist(L2);
    Listnode* long_list=NULL;
    Listnode* short_list=NULL;
    
    if(L1_length&&L2_length)
        return NULL;
    int i=0;
    if(L1_length>=L2_length)
    {
        long_list=L1;
        short_list=L2;
        i=L1_length-L2_length;
    }
    else
    {
        long_list=L2;
        short_list=L1;
        i=L2_length-L1_length;
    }
    while(i)
    {
        i--;
        long_list=long_list->next;
    }
    while(long_list&&short_list&&(long_list==short_list))
    {
        long_list=long_list->next;
        short_list=short_list->next;
    }
    if(long_list==short_list)
        return long_list;
    else
        return NULL;
}

 

posted on 2017-05-03 16:55  kiplove  阅读(180)  评论(0编辑  收藏  举报

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