链表的面试题(二)

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最新推荐文章于 2025-02-24 17:44:03 发布

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分类专栏： C++ 文章标签：面试题单链表链表

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完成链表的以下操作：

// 使用冒泡对单链表进行排序
void BubbleSort(PNode pHead)

// 合并两个已序链表，合并之后新链表依然有序
PNode MergeList(PNode pHead1, PNode pHead2)

// 查找无头单链表的倒数第K个结点
PNode FindLastKNode(PNode pHead, int K)；

// 删除无头单链表的倒数第K个结点
PNode DeleteLastKNode(PNode pHead, int K)；

// 判断链表是否带环，如果带环求环的长度，并给出入口点
PNode HasCircle(PNode pHead)；
int GetCircleLen(PNode pHead)；
PNode GetEnterNode(PNode pHead, PNode pMeetNode)；

源程序

void BubbleSort(PNode pHead)//冒泡排序
{
    if (NULL == pHead || NULL == pHead->next)
    {
        return;
    }
    PNode pCur = pHead;
    PNode pTail = NULL;
    int flag = 0;
    while (pTail != pHead)
    {
        pCur = pHead;
        while (pCur->next != pTail)
        {
            if (pCur->data > pCur->next->data)
            {
                DataType tmp = pCur->data;
                pCur->data = pCur->next->data;
                pCur->next->data = tmp;
                flag = 1;
            }
            pCur = pCur->next;
            if (!flag)
            {
                return;
            }
        }
        pTail = pCur;
    }
}

这里写图片描述

PNode FindLastKNode(PNode pHead, int K)
{
    if (NULL == pHead || K == 0)
    {
        return NULL;
    }
    PNode pSlow = pHead;
    PNode pFast = pHead;
    while (--K)
    {
        if (NULL == pFast)
        {
            return NULL;
        }
        pFast = pFast->next;
    }
    while (pFast->next)
    {
        pSlow = pSlow->next;
        pFast = pFast->next;
    }
    return pSlow;
}

void DeleteLastKNode(PNode pHead, int  K)
{
    if (NULL == pHead || K == 0)
    {
        return;
    }
    PNode pos = FindLastKNode(pHead, K);
    Erase(pHead, pos);

PNode MergeList(PNode pHead1, PNode pHead2);
考虑以下因素:
pHead1为空—–返回pHead2
pHead2为空—–返回pHead1
当pHead1和pHead2都不为空时，分析如图示：
这里写图片描述

PNode MergeList(PNode pHead1, PNode pHead2)
{
    if (NULL == pHead1)
    {
        return pHead2;
    }
    if (NULL == pHead2)
    {
        return pHead1;
    }
    PNode newNode = NULL;
    PNode pTail = NULL;
    if (pHead1->data < pHead2->data)
    {
        pTail = pHead1;
        pHead1 = pHead1->next;
    }
    else
    {
        pTail = pHead2;
        pHead2 = pHead2->next;
    }
    newNode = pTail;
    while (pHead1 && pHead2)
    {
        if (pHead1->data < pHead2->data)
        {
            pTail->next = pHead1;
            pTail = pHead1;
            pHead1 = pHead1->next;
        }
        else
        {
            pTail->next = pHead2;
            pTail = pHead2;
            pHead2 = pHead2->next;
        }
    }
    if (pHead1)
    {
        pTail->next = pHead1;
    }
    else
    {
        pTail->next = pHead2;
    }
    return newNode;
}

// 判断链表是否带环，若带环给出相遇点  
PNode HasCircle(PNode pHead)

{
    if (pHead == NULL)
    {
        return NULL;
    }
    else
    {

        PNode pFast = pHead;
        PNode pSlow = pHead;
        {
            while (pFast && pFast->next)
            {
                pSlow = pSlow->next;
                pFast = pFast->next->next;
                if (pFast == pSlow)
                {
                    return pSlow;
                }
            }
            return NULL;
        }
    }
}

// 求环的长度  
int   GetCircleLen(PNode pMeetNode)
{
    PNode pCurNode = pMeetNode;
    int count = 1;
    while (pCurNode->next != pMeetNode)
    {
        pCurNode = pCurNode->next;
        count++;
    }
    return count;
}

// 求环的入口点  
PNode GetEnterNode(PNode pHead, PNode pMeetNode)

{
    if (pHead == NULL)
    {
        return NULL;
    }
    else
    {
        PNode pFast = pHead;
        PNode pSlow = pMeetNode;
        {
            while (pFast != pSlow)
            {
                pSlow = pSlow->next;
                pFast = pFast->next;
            }
            return pSlow;
        }
    }
}