链表操作面试题

#include<stdio.h> #include<stdlib.h> #include<assert.h>#define DateType int typedef struct Node {    DateType data;    struct Node* next;}Node, *pNode;void PrintList(pNode head)//打印链表 {    pNode tmp = head;    while (tmp)    {        printf("%d-->", tmp->data);        tmp = tmp->next;    } printf("NULL\n");}void BubbleSort(pNode *pHead)// 使用冒泡对单链表进行排序{    pNode p = NULL, q = NULL, ptail = NULL;    int cmp, tag = 0;    assert(pHead);    if (*pHead == NULL || (*pHead)->next == NULL)        return;    p = *pHead;    q = *pHead;    while (p)    {        q = *pHead;        tag = 0;        while (q->next != ptail)        {            if (q->data > q->next->data)            {                cmp = q->data;                q->data = q->next->data;                q->next->data = cmp;                tag = 1;            }            q = q->next;        }        if (tag == 0)            return;        ptail = q;        p = p->next;    }}pNode MergeList(pNode pHead1, pNode pHead2)// 合并两个已序链表，合并之后新链表依然有序{    pNode pl1 = NULL, pl2 = NULL,pnewhead=NULL,ptail=NULL;    assert(pHead1||pHead2);    pl1 = pHead1;    pl2 = pHead2;    if (!pl1)        return pl2;    if (!pl2)        return pl1;    if (pl1->data < pl2->data)    {        pnewhead = pl1;        ptail = pl1;        pl1 = pl1->next;    }    else    {        pnewhead = pl2;        ptail = pl2;        pl2 = pl2->next;    }    while (pl1&&pl2)    {        if (pl1->data < pl2->data)        {            ptail->next  = pl1;            ptail = pl1;            pl1 = pl1->next;        }        else        {            ptail->next  = pl2;            ptail = pl2;            pl2 = pl2->next;        }    }    if (!pl1)        ptail->next = pl2;    else ptail->next = pl1;    return pnewhead;}pNode FindLastKNode(pNode pHead, int K)// 查找无头单链表的倒数第K个结点{    pNode pleft = NULL, pright = NULL;    assert(pHead);    if (pHead == NULL|| K <= 0)        return NULL;    pleft = pright = pHead;    while (--K)    {        if (pright->next == NULL)            return NULL;        pright = pright->next;    }    while (pright->next !=NULL)    {        pright = pright->next;        pleft = pleft->next;    }    return pleft;}pNode DeleteLastKNode(pNode pHead, int K)// 删除无头单链表的倒数第K个结点{    pNode pdelnode = NULL, pdelleftnode = NULL;    pdelnode=FindLastKNode(pHead, K);    if (pdelnode == NULL)    {        printf("要删除的节点不存在！！！\n");        return NULL;    }    else if (pdelnode == pHead)    {        pdelleftnode = pdelnode;        pHead = pHead->next;        free(pdelnode);        pdelnode = NULL;    }    else    {        pdelleftnode = FindLastKNode(pHead, K+1);        pdelleftnode->next = pdelnode->next;        free(pdelnode);        pdelnode = NULL;    }    return pHead;}// 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)//判断链表是否带环{    pNode  pleft = NULL, pright = NULL;    assert(pHead);    if (pHead == NULL || pHead->next == NULL)        return NULL;    pleft = pHead;    pright = pHead->next;    while (pright || pright->next)    {        if (pleft != pright)        {            pleft = pleft->next;            pright = pright->next->next;        }        else return pleft;    }    return NULL;}int GetCircleLen(pNode pHead)//如果带环,求环的长度{    pNode ptail=HasCircle(pHead);    pNode q = ptail->next ;    int counter=1;    assert(pHead);    if (ptail == NULL)        return 0;    while (q != ptail)    {        counter++;        q = q->next;    }    return counter;}pNode GetEnterNode(pNode pHead, pNode pMeetNode)//给出带环入口点{    pNode  ptail = NULL, q = NULL;    ptail =pMeetNode;    q = pHead;    while (q==ptail)    {        q = q->next;        ptail = ptail->next;    }    return q;}void test(){    pNode list1;    pNode list2;    pNode pos;    pNode q;    InitList(&list1);    PushBack(&list1,7);    //7->NULL     PushBack(&list1, 5);    //7->5->NULL     PushBack(&list1, 3);    //7->5->3->NULL     PrintList(list1);    InitList(&list2);    PushBack(&list2, 1);    //1->NULL     PushBack(&list2, 4);    //1->4->NULL     PushBack(&list2, 8);    //1->4->8->NULL     PrintList(list2);    BubbleSort(&list1);    PrintList(list1);    //3->5->7->NULL     q=MergeList(list1,list2);    PrintList(q);    //1->3->4->5->7->8->NULL     pos=FindLastKNode(q,2);    if (pos == NULL)        printf("没有找到合适的值！！！\n");    else printf("%d\n",pos->data);    //7    pos=DeleteLastKNode(q, 2);    if (pos == NULL)        printf("没能删除合适的值！！！\n");    else    PrintList(pos);    //1->3->4->5->8->NULL }int main(void){    test();    return 0;}