Re: Ordered Sorted List

[Richard Knutsson <ricknu-0@student.ltu.se>]

Nanakos Chrysostomos wrote:

> Hi ,all.Can someone please explain this source code with an example???
>
>  
Homework?

> ***********************************************************************
> #include <stdio.h>
>
> typedef struct list_tag {
>        int data;
>        struct list_tag *next;
> }ListNode;
>
> typedef ListNode *slist;
> slist empty = NULL;
>
> void slistInsert(slist *sp,int t)
> {
>        ListNode *n=(ListNode *)malloc(sizeof(ListNode));
>        if(n == NULL)
>        {
>                printf("Out of memory\n");
>                exit(1);
>        }
>        n->data = t;
>        while(*sp!=NULL && (*sp)->data < t)
>        {
>        sp = &((*sp)->next);   //Why we do this here,i miss this point
>        }
>  
This is a _sorted_ list, right. So somehow we have to sort it.
What it does is to either find a node with a value higher then 't', or 
it reach the end of the list. Meanwhile, it just continue walking the list.

>        n->next = *sp;
>        *sp = n;
>  
... so here we hock the rest of the list with the new node.

> }
>
>
> void slistRemove(slist *sp,int t)
> {
>        ListNode *n;
>        while(*sp!=NULL && (*sp)->data <t)
>                sp = &((*sp)->next);
>        if(*sp == NULL)
>        {
>                printf("Not found\n");
>                exit(1);
>        }
>
>        n=*sp;
>        *sp = (*sp)->next;
>        free(n);
> }
>
> void slistPrint(slist s)
> {
>        ListNode *n;
>        for(n=s;n!=NULL; n=n->next)
>                printf("%d\n",n->data);
> }
>
> void main()
> {
>
>  
NULL

>      slistInsert(&empty,4);
>  
4->NULL

>      slistInsert(&empty,8);
>  
4->8->NULL

>      slistInsert(&empty,24);
4->8->24->NULL

>      slistInsert(&empty,50);
>  
4->8->24->50->NULL

>      slistInsert(&empty,20);
>  
4->8->20->24->50->NULL

>      slistInsert(&empty,2);
>  
2->4->8->20->24->50->NULL

>      slistRemove(&empty,4);
>  
Remove first value equal or more than 4.
2->8->20->24->50->NULL

>      slistInsert(&empty,18);
>  
2->8->18->20->24->50->NULL

>      slistPrint(empty);
>  
2
8
18
20
24
50

> }
>
> Thank you very much in advance.
>  
cu
/Richard Knutsson
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