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deleting nodes from a linked list structure

Posted on 2000-03-01
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Last Modified: 2012-05-04
My problem deals with deletions of nodes from a linked list structure. the nodes in the linked list are defined by the type definitions given as:
    typedef struct node
      {
       int value;             /*value of node*/
       struct node next;      /*points to next node in list*/
       struct node previous;  /*points to the previous node in list*/
      }NodeRec;

    typedef Noderec *node_ptr;

the forward pointers (next) for the nodes follow the node values in sorted order from smallest to largest. the backward pointer (previous) for each node points to its predecessor as determined by the sorted ordering.
a linked listed created  with this structure has both a head pointer which points to the first node (smallest valued node) in the list and a tail pointer pointing to the last node (largest valued node) in the list. I need to write a function that will remove a node from the linked list. the function will modify list pointers as necessary so as to leave the remainder of the list intact. a call to the function will be of the form:
            found = remove(item,head,tail);
where head points to the first node in the list, tail points to the last node in the list and item is the integer value of the node to be deleted from the list. head and tail are both of type node_ptr. the variable found is of type boolean. remove returns TRUE if the value to be deleted has been found in the list. remove returns FALSE if the value to be deleted could not be found in the list. make sure that the function considers three cases. one case will be the deletion of the head node of the list. a second case will be the deletion of the tail node of the list. a third case will be the deletion of a node somewhere in the middle of the list. if multiple occurences of a given value to be deleted occur in the list, delete only the node containing the first occurence of the value.........thanks in advance!
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Question by:beachbumm
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3 Comments
 
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Expert Comment

by:Wyn
ID: 2573184
bool remove(item,head,tail)
{  node_ptr temp=head;
    while(temp){
        if(temp->value==item){
        if(temp==head){
        temp->next->previous=NULL;
        head=temp->next;
        return TRUE;
         }
        if(temp==tail){
        temp->previous->next=NULL;
        tail=temp->previous;
        return TRUE;
        }
        temp->previous->next=temp->next;
        temp->next->previous=temp->previous;
return TRUE;
}//if
        temp=temp->next;
}//while

     return FALSE;

}

Regards
W.Yinan

       
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LVL 5

Expert Comment

by:Wyn
ID: 2573186
bool remove(item,head,tail)
{  node_ptr temp=head;
    while(temp){
        if(temp->value==item){
        if(temp==head){
        temp->next->previous=NULL;
        head=temp->next;
        return TRUE;
         }
        if(temp==tail){
        temp->previous->next=NULL;
        tail=temp->previous;
        return TRUE;
        }
        temp->previous->next=temp->next;
        temp->next->previous=temp->previous;
return TRUE;
}//if
        temp=temp->next;
}//while

     return FALSE;

}

Regards
W.Yinan

       
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Accepted Solution

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Wyn earned 200 total points
ID: 2573187
hmmm...
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