Question

Deleting multiples of a given integer from a linked list:

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#define MAX 10000

typedef struct node_tag
{
int v; // data
struct node_tag * next; // A pointer to this type of struct
} node; // Define a type. Easier to use.

node * create_node(int v)
{
node * p = malloc(sizeof(node)); // Allocate memory
assert(p != NULL); // you can be nicer

// Set the value in the node.
p->v = v;
p->next = NULL;
return p; // return
}

//Print the list
void print_list(node *head)
{   
while(head!=NULL)
{   
printf("%d ", head->v);
head = head->next;
}
printf("\n");
}

//Add newnode at the head of the list
void add_first(node **head, node *newnode)
{
if(*head == NULL)
{
*head = newnode;
newnode->next = NULL;
}
else
{
newnode->next = *head;
*head = newnode;
}
}

//Remove the first node from the list
node * remove_first(node **head)
{
   node *p;

   p = (*head);
   if((*head)!=NULL) (*head) = (*head)->next;
   return p;
}

//Remove all the nodes whose value is a multiple of k but not k itself from the list, and free
//their allocated memory
void remove_multiple(node **head, int k)
{   
print_list(*head);
printf("Remove multiples of %d\n", k);
  
val = head->next;
  
  
if (*head == NULL;)
{
return;
}
while (*head != NULL)
{
if (*head % k == 0)
{
  
}
}

}

//Remove all the nodes from the list and free the corresponding memory
void free_all(node **head)
{

}

//Return the number of items in the list
int list_length(node *head)
{

}
//Do not change the main function
int main(int argc, char *argv[])
{
if(argc!=2)
{
printf("Usage: %s n\n", argv[0]);
return -1;
}
int n = atoi(argv[1]);
assert(n >= 1 && n <= MAX);
node *head, *p;
head = NULL;

int i;

for(i=n; i>=2; i--)
{
p = create_node(i);
add_first(&head, p);
}

for(i = 2; i<n; i++)
{
remove_multiple(&head, i);
}

printf("%d primes between 1 and %d:\n", list_length(head), n);
print_list(head);
free_all(&head);
printf("%d items left in the list after free_all().\n", list_length(head));
return 0;
}

Answer 1

#define _CRT_SECURE_NO_DEPRECATE
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#define MAX 10000

typedef struct node_tag
{
   int v; // data
   struct node_tag * next; // A pointer to this type of struct
} node; // Define a type. Easier to use.

node * create_node(int v)
{
   node * p = malloc(sizeof(node)); // Allocate memory
   assert(p != NULL); // you can be nicer

                   // Set the value in the node.
   p->v = v;
   p->next = NULL;
   return p; // return
}

//Print the list
void print_list(node *head)
{
   while (head != NULL)
   {
       printf("%d ", head->v);
       head = head->next;
   }
   printf("\n");
}

//Add newnode at the head of the list
void add_first(node **head, node *newnode)
{
   if (*head == NULL)
   {
       *head = newnode;
       newnode->next = NULL;
   }
   else
   {
       newnode->next = *head;
       *head = newnode;
   }
}

//Remove the first node from the list
node * remove_first(node **head)
{
   node *p;

   p = (*head);
   if ((*head) != NULL) (*head) = (*head)->next;
   return p;
}

//Remove all the nodes whose value is a multiple of k but not k itself from the list, and free
//their allocated memory
void remove_multiple(node **head, int k)
{
   int first = 0;
   node *cur = *head,*prev=NULL,*next=NULL;
   print_list(*head);
   printf("Remove multiples of %d\n", k);
   while (cur != NULL)
   {
      
       if (cur->next != NULL)
       {
           if (cur->v%k == 0 )
           {
               if (first == 0)
               {
                   ++first;
               }
               else
               {
                   //delete this node
                   if(prev!=NULL)
                   if (prev->next != NULL)
                   {
                       next = prev->next->next;
                       prev->next = cur->next;
                       free(cur);
                       //cur = NULL;
                       cur = next;
                       ++first;
                   }
               }
           }
       }
       else
       {
           //++first;
           if (first != 0 && cur->v%k == 0)
           {
               next = prev->next->next;
               prev->next = cur->next;
               free(cur);
               //cur = NULL;
               cur = next;
           }
          
       }
       prev = cur;
       if(cur!=NULL)
       cur = cur->next;
   }
  

}

//Remove all the nodes from the list and free the corresponding memory
void free_all(node **head)
{
   node *cur = *head,*tmp;
   while (cur != NULL)
   {
       tmp = cur->next;
       free(cur);
       cur = tmp;
   }
   *head = NULL;
}

//Return the number of items in the list
int list_length(node *head)
{
   node *cur = head;
   int count = 0;
   while (cur != NULL)
   {
       ++count;
       cur = cur->next;
   }
   return count;
}
//Do not change the main function
int main(int argc, char *argv[])
{
   if (argc != 2)
   {
       printf("Usage: %s n\n", argv[0]);
       return -1;
   }
   int n = atoi(argv[1]);
   assert(n >= 1 && n <= MAX);
   //int n = 30;
   node *head, *p;
   head = NULL;

   int i;

   for (i = n; i >= 2; i--)
   {
       p = create_node(i);
       add_first(&head, p);
   }

   for (i = 2; i<n; i++)
   {
       remove_multiple(&head, i);
   }

   printf("%d primes between 1 and %d:\n", list_length(head), n);
   print_list(head);
   free_all(&head);
   printf("%d items left in the list after free_all().\n", list_length(head));
   return 0;
}

==========================

//output

2 3 4 5 6 7 8 9 10 11 12 13 14 15                                                                                                

Remove multiples of 2                                                                                                            

2 3 5 7 9 11 13 15                                                                                                               

Remove multiples of 3                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 4                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 5                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 6                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 7                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 8                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 9                                                                                                            

2 3 5 7 11 13                                                                                                                    

Remove multiples of 10                                                                                                           

2 3 5 7 11 13                                                                                                                    

Remove multiples of 11                                                                                                           

2 3 5 7 11 13                                                                                                                    

Remove multiples of 12                                                                                                           

2 3 5 7 11 13                                                                                                                    

Remove multiples of 13                                                                                                           

2 3 5 7 11 13                                                                                                                    

Remove multiples of 14                                                                                                           

6 primes between 1 and 15:                                                                                                       

2 3 5 7 11 13                                                                                                                    

0 items left in the list after free_all().