单链表基本操作

单链表的各类基本操作包括：链表的创建、删除、插入、输出、排序（选择、冒泡）、逆置等。还有一些单链表相关题目：遍历一次查找中间节点或倒数第k个节点。

# include<stdio.h># include<assert.h># include<stdlib.h>typedef int DataType;typedef struct ListNode{    DataType data;    struct ListNode* next;}ListNode;ListNode* BuyNode(DataType x){    ListNode* tmp = (ListNode*)malloc(sizeof (ListNode));    assert(tmp);    tmp->data = x;    tmp->next = NULL;    return tmp;}void print(ListNode* pHead){    ListNode* cur = pHead;    while (cur)    {        printf("%d-> ",cur->data);        cur = cur->next;    }    printf("NULL\n");}void PushBack(ListNode*& pHead,DataType x){    if (NULL == pHead)    {        pHead = BuyNode(x);        return;    }    else    {        ListNode* tail = pHead;        while (tail->next)        {            tail = tail->next;        }        tail->next = BuyNode(x);    }}void PopBack(ListNode*& head){    if (NULL == head)    {        printf("list is empty!\n");        return;    }    else if ( head->next == NULL)    {        free(head);        head = NULL;    }    else    {        ListNode *prev = NULL,*tail = head;        while (tail->next != NULL)        {            prev = tail;            tail = tail->next;        }        prev->next = NULL;        free(tail);    }}void PushFront(ListNode*& head,DataType x){    if (NULL == head)    {        head = BuyNode(x);    }    else    {        ListNode* tmp = BuyNode(x);        tmp->next = head;        head = tmp;    }}void PopFront(ListNode*& head){    if (NULL == head)    {        printf("empty!\n");        return;    }    ListNode* prev = head;    prev = head->next;    free(head);    head = prev;}void Insert(ListNode* pos,DataType x){    assert(pos);    ListNode* tmp = BuyNode(x);    tmp->next = pos->next;    pos->next = tmp;}void Erase(ListNode* pos,ListNode*& head){    assert(pos);    ListNode* prev = NULL,*cur = head;    while (cur)    {        if (cur == pos)        {            prev->next = cur->next;            free(cur);            cur = NULL;            return;        }        prev = cur;        cur = cur->next;    }    printf("the position not exist\n ");}ListNode* Find(ListNode* head,DataType x){    ListNode* cur = head;    while (cur)    {        if (cur->data == x)        {            return cur;        }        cur = cur->next;    }    return NULL;}void Remove(ListNode*& head,DataType x){    ListNode* tmp = Find(head,x);    if (NULL != tmp)    {        Erase(tmp,head);    }    else    {        printf("%d is not exsit\n");    }}int getLength(ListNode* pHead){    assert(pHead);    ListNode* cur = pHead;    int count = 0;    while(cur)    {        count++;        cur = cur->next;    }    return count;}void Swap(DataType* x,DataType* y){    DataType tmp = *x;    *x = *y;    *y = tmp;}/*删除一个无头单链表的非尾结点*//*把pos->next的值给pos,然后删掉pos->next*/void DelNonTailNode(ListNode* pos){    assert(pos && pos->next);    pos->data = pos->next->data;    ListNode* _next = pos->next->next;    free(pos->next);    pos->next = NULL;    pos->next = _next;}/*在无头单链表非头结点前插入结点*//*在pos后面插入节点，交换pos和pos->next的data*/void InsertFrontNode(ListNode* pos,DataType x){    assert(pos);    ListNode* tmp = BuyNode(x);    tmp->next = pos->next;    pos->next = tmp;    Swap(&pos->data,&tmp->data);}/*单链表逆置*/void Reverse(ListNode*& pHead){    ListNode* cur = pHead;    ListNode* newHead = NULL;    while (cur)    {        ListNode* tmp = cur;        cur = cur->next;        tmp->next = newHead;        newHead = tmp;    }    pHead = newHead;}/*遍历一次查找中间结点*/ListNode* FindMidNode(ListNode* pHead){    assert(pHead);    ListNode* slow = pHead;    ListNode* fast = pHead;    while (fast && fast->next)    {        fast = fast->next->next;        slow = slow->next;    }    return slow;}/*遍历一次查找倒数第个结点*//*fast指针先走k步，两个指针再一起走，当fast指针指向空时，返回slow*/ListNode* FindBackNode(ListNode* pHead,int k){    assert(pHead);    ListNode* slow = pHead;    ListNode* fast = pHead;    while (k != 0 && fast)       {        fast = fast->next;        k--;    }    if (k != 0)    {        printf("the node not exsit!\n");        return NULL;    }    while (fast)    {        fast = fast->next;        slow = slow->next;    }    return slow;}/*单链表冒泡排序*/void BubbleSort(ListNode*& pHead){    int flag = 0;    int count = getLength(pHead);    int len = count;    ListNode* cur = NULL;    while (count)    {        cur = pHead;        len = count - 1;        while (len)        {            if (cur->data > cur->next->data)            {                Swap(&cur->data,&cur->next->data);                flag = 1;            }            cur = cur->next;            len -= 1;        }        if (0 == flag)        {            return;        }        count -= 1;    }}/*单链表选择排序*/void SelectSort(ListNode*& pHead){    ListNode* cur = pHead;    ListNode* prev = cur;    while (prev)    {        cur = prev->next;        while (cur)        {            if (prev->data > cur->data)            {                Swap(&prev->data,&cur->data);            }            cur = cur->next;        }        prev = prev->next;    }}void DestoryList(ListNode*& pHead){    ListNode* cur = pHead;    while(cur)    {        ListNode* tmp = cur;        cur = cur->next ;        free(tmp);        tmp = NULL;    }}//测试void Test1(ListNode*& pHead){    printf("Test1:\n");    PushBack(pHead,3);    PushBack(pHead,5);    PushBack(pHead,1);    PushBack(pHead,6);    PushBack(pHead,2);    PushBack(pHead,4);    print(pHead);    printf("冒泡排序：\n");    BubbleSort(pHead);    print(pHead);    printf("逆置：\n");    Reverse(pHead);    print(pHead);}void Test2(ListNode*& pHead){    printf("\nTest2:\n");    pHead = NULL;    PushBack(pHead,3);    PushBack(pHead,5);    PushBack(pHead,1);    PushBack(pHead,6);    PushBack(pHead,2);    PushBack(pHead,4);    print(pHead);    printf("查找倒数第三个结点：\n");    ListNode* tmp = FindBackNode(pHead,3);    printf("the node you found is %d\n",tmp->data);    printf("在倒数第三个结点前插入结点:8\n");    InsertFrontNode(tmp,8);    print(pHead);    printf("选择排序：\n");    SelectSort(pHead);    print(pHead);    printf("查找中间结点：\n");    printf("the middle node is %d\n",FindMidNode(pHead)->data );    printf("删除无头非尾结点：\n");    DelNonTailNode(tmp);    print(pHead);}int main(){    ListNode* list;    list = NULL;    Test1(list);    Test2(list);    DestoryList(list);    return 0;}