1.单向链表

#include<stdio.h>
#include<stdlib.h>

typedef struct Node{

    int elem;
    struct Node *next;

}Node,*List;

List createList();  //创建空链表
void insertList(List list, int elem);  //链表插入元素
void deleteList(List list, int elem);  //链表删除元素
int  lengthList(List list);  //链表长度
void reverse(List list);    //链表反转
void reverse2(List list);    //链表反转
void traversal(List list);    //链表遍历
Node *findKthTotail(List list,int k); //找到链表的倒数第k个元素

List createList(){

    List list ;
    list = (Node *)malloc(sizeof(Node));
    if(list == NULL)
        printf("内存不足，链表创建失败");
    else
    {
        list->next=NULL;
        list->elem=0;
        return list;
    }
    return NULL;

}

void insertList(List list, int elem){
    
    Node *insertnode;
    Node *firstNode;
    insertnode = (List)malloc(sizeof(Node));
    if(insertnode == NULL)
        printf("内存不足，插入创建失败");
    else
    {    
        insertnode->elem = elem;
        firstNode = list->next;
        list->next = insertnode;
        if(firstNode == NULL)   
            insertnode->next = NULL;
        else
            insertnode->next = firstNode;
    }

}
void deleteList(List list, int elem){
  
    Node *t=list->next;
    Node *p=list;
    while(t!=NULL){
           if(t->elem!=elem)
           {   
               p=t;
               t=t->next;
           }               
           else{
                p->next=t->next;
                free(t);
                break;
           }
    }

}

int lengthList(List list){

    int length=0;
    while(list->next != NULL){
        length++;
        list=list->next;
    }    
    return length;

}

void reverse(List list){

    Node *t = list;
    Node *p = t->next;
    Node *q = p->next;
    if(p == NULL||q == NULL)
        return;
    else{
        Node *temp;
        Node *temp1=p;
        while(q != NULL){
            t->next = q;
            temp = q->next;
            q->next = p;
            p = q;
            q = temp;
        }
        temp1->next=NULL;
    }

}

void reverse2(List list){

    Node *t = list;
    Node *p = t->next;
    Node *q;
    while(p->next != NULL){
        q = p->next;
        p->next = t;
        t = p;
        p = q;
    }
     p->next=t;
     list->next->next = NULL;
     list->next = p;

}

void traversal(List list){

    Node *t=list->next;
    while(t!=NULL){
        printf("%d ",t->elem);
        t=t->next;
    }

}


Node *findKthTotail(List list,int k){ //找到链表的倒数第k个元素

    Node *pre;
    Node *current = list;
    int i;
    for(i = 0;i < k-1 && current != NULL;i++){
        current = current->next;
    }
    if(i==k-1)
    {
        pre =list;
        while(current->next!=NULL){
            current = current->next;
            pre=pre->next;
        }
        return pre;
    }else
        return NULL;

} 

void main(){

    List list;
    int length;
    list = createList(); //带头结点链表
    
    insertList(list,3); //添加元素
    insertList(list,4);
    insertList(list,5);
    
    deleteList(list,5); //删除加元素
    insertList(list,5);
    insertList(list,6);

    printf("反转前:");
    traversal(list);

    reverse2(list);
    printf("反转后:");
    traversal(list);
    
    length = lengthList(list);
    printf("list length is %d\n",length);  


}