c – 链接列表：使用最后一个指针在末尾插入

基本思想是* HEAD指向列表的第一个元素,* LAST指向最后一个元素.这样可以节省遍历列表最后一个元素然后添加元素的时间和计算.

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

// Structure for the list element/node
struct node 
{
 int data; // Stores the data
 struct node *next; // Points to the next element in the list.
};

int InsertAtEnd(struct node **,struct node **,int); /*Declaration of the function which 
                                                    inserts elements at the end.*/

int main()
{
 struct node *HEAD=NULL; //Points to the first element in the list.
 struct node *LAST=NULL; //Points to the last element in the list.
 int i=1;

 for(i=1;i<11;i++)
   {
     InsertAtEnd(&HEAD,&LAST,i);
   }
 }

// Function to insert element at the end.
int InsertAtEnd(struct node **headref,struct node **lastref,int i)
 {
   struct node *newnode=malloc(sizeof(struct node)); /*Allocates memory for the newnode 
                                                     and store the address in pointer 
                                                     newnode*/
   newnode->data=i; // Assign value to the data variable of the newnode.
   newnode->next=NULL; // Assign NULL to the next pointer of the newnode.

   if(*headref==NULL) //Checks if the list is empty.
    {
      *headref=newnode; // Places the address of the new node in HEAD pointer.
      *lastref=newnode; // Places the address of the new node in LAST pointer.

       return 0; //Exit function
    }

/* If the list is not empty,then make the next pointer of the present last node point to the new node*/

   (*lastref)->next=newnode;

   *lastref=(*lastref)->next; // Increment LAST to point to the new last node.

    return 0;
}

我想特别提出的问题是：

a)上面添加元素的代码(即InsertAtEnd函数)是否正确？ (注意：我在我的机器上进行了测试,它按预期工作.但我还是要向你们确认)

b)代码(InsertAtEnd函数)是否有效？

c)如果我尝试制作更长的列表,是否会影响代码(InsertAtEnd函数)的效率.

d)是否有更有效和简单的算法来插入元素？你能指导我吗？