Split Circular Linked List In C

Implementation

Implementation of this algorithm is given below −

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

struct node {
   int data;
   struct node *next;
};

struct node *even = NULL;
struct node *odd = NULL;
struct node *list = NULL;

//Create Linked List
void insert(int data) {
   // Allocate memory for new node;
   struct node *link = (struct node*) malloc(sizeof(struct node));
   struct node *current;

   link->data = data;
   link->next = NULL;

   if(list == NULL) {
      list = link;
      list->next = link;
      return;
   }
   current = list;

   while(current->next != list)
      current = current->next;

   // Insert link at the end of the list
   current->next = link; 
   link->next = list;
}

void display(struct node *head) {
   struct node *ptr = head;

   printf("[head] =>");
   //start from the beginning
   while(ptr->next != head) {        
      printf(" %d =>",ptr->data);
      ptr = ptr->next;
   }
   printf(" %d =>",ptr->data);
   printf(" [head]\n");
}

void split_list() {
   int count = 0;
   // Allocate memory for new node;
   struct node *list1;
   struct node *link;
   struct node *current;
   
   list1 = list;

   while(list1->next != list) {
      struct node *link = (struct node*) malloc(sizeof(struct node));

      link->data = list1->data;
      link->next = NULL;

      if(list1->data%2 == 0) {

         if(even == NULL) {
            even = link;
            even->next = link;
            list1 = list1->next;
            continue;
         } else {
            current = even;

            while(current->next != even) {
               current = current->next;
            }

            // Insert link at the end of the list
            current->next = link; 
            link->next = even;
         }
         list1 = list1->next;
      
      } else {
         if(odd == NULL) {
            odd = link;
            odd->next = link;
            list1 = list1->next;
            continue;
         
         } else {
            current = odd;
            while(current->next!= odd) {
               current = current->next;
            }
            
            // Insert link at the end of the list
            current->next = link; 
            link->next = odd;

         }
         list1 = list1->next;
      }
   }
   
   // Lets handle the last node
   link = (struct node*) malloc(sizeof(struct node));
     
   link->data = list1->data;
   link->next = NULL;
   if(list1->data%2 == 0) {
      current = even;

      while(current->next != even) {
         current = current->next;
      }

      // Insert link at the end of the list
      current->next = link; 
      link->next = even;
   } else {
      current = odd;
        
      while(current->next!= odd) {
         current = current->next;
      }
      
      // Insert link at the end of the list
      current->next = link; 
      link->next = odd;
   }
}

int main() {
   int i;

   for(i = 1; i <= 10; i++)
      insert(i);

   printf("Complete list: \n");
   display(list);

   split_list();

   printf("\nOdd  : ");
   display(odd);

   printf("Even : ");
   display(even);

   return 0;
}

Output

Output of the program should be −

Complete list:
[head] => 1 => 2 => 3 => 4 => 5 => 6 => 7 => 8 => 9 => 10 => [head]

Odd  : [head] => 1 => 3 => 5 => 7 => 9 => [head]
Even : [head] => 2 => 4 => 6 => 8 => 10 => [head]