GeeksforGeeks

GeeksforGeeks » Algorithms

Linked List

(5 posts)

1. 

   Kamal
   Member
   Posted 3 months ago #
   
   

   Given a linked list as follows:
   a->b->c->1->2->3
   Arrange it in a manner it would return
   a->1->b->2->c->3
   Note:list contains even number of nodes.

2. 

   atul007
   Member
   Posted 3 months ago #
   
   

   maintain two stack...
   in stack1 keep on pushing the nodes until some node->data!=numeric value;
   now push all numeric node in the stack2.

   n1=pop(stack2);
   n2=pop(stack1);
   n1->next=n2;

   keep on doing that until both stack are null

3. 

   atul007
   Member
   Posted 3 months ago #
   
   

   2nd method :

   maintain one ptr1 at head.

   increment ptr2 till it reaches a node which has numeric value...in the given example its "1";

   now remove node at ptr2 and add it to the next of ptr1;
   increment ptr1 twice.

4. 

   vikram.kuruguntla
   Member
   Posted 3 months ago #
   
   

   @atul007
   increment ptr2 till it reaches a node which has numeric value...in the given example its "1";

   I think ptr2 should point to the node before 1( which is c), but not the 1. As we need to connect c and 2 after linking node 1 between a and b nodes.

   lets ptr1 points to a
   lets ptr2 points to c ( which is node before 1 )

   1> temp = ptr2->next->next ( save node after 1 which is 2 in temp)
   insert 1 between a and b
   2> ptr2->next->next = ptr1->next ( make 1's next, point to b)
   3> ptr1->next = ptr2->next; ( make a's next, point to 1)

   connect c and 2
   4> ptr2->next = temp; (make c's next, point to 2)

   5> ptr1 = ptr1->next->next; (lets ptr1 point to b)

   Repeat steps from 1-6 until ptr1 reaches ptr2. Or ptr2->next reaches NULL.

   Thanks.

5. 

   PsychoCoder
   Member
   Posted 3 months ago #
   
   

   #include<stdio.h>
   #include<stdlib.h>
   #include<ctype.h>
   
   typedef struct node {
     char data ;
     struct node *next ;
   }node ;
   
   node* createNode (char ch) {
     node *head ;
     head = (node *) malloc (sizeof(node)) ;
     head->data = ch ;
     head->next = NULL ;
     return head ;
   }
   
   node* getData () {
     int size, i ;
     char ch;
     node *head = NULL, *temp;
     printf ( "\nEnter the size of the string :\t " ) ;
     scanf ( "%d", &size ) ;
     for ( i = 0 ; i < size ; i ++ ) {
       printf ( "\nEnter the %d the character:\t",i+1 ) ;
       do {
         scanf ( "%c", &ch );
       } while (!isalnum(ch));
       if (head == NULL){
         head = createNode (ch) ;
         temp = head ;
       } else {
         temp->next = createNode (ch) ;
         temp = temp->next ;
       }
     }
     return head ;
   }
   
   void printList (node *head) {
     node* list = head ;
     printf ( "\n\n" ) ;
     while (list) {
       printf ( "%c", list->data ) ;
       list = list->next ;
     }
   }
   
   node* performOperation (node* head) {
     node *ptr1, *temp, *ptr2 ;
     ptr2 = head ;
     while (ptr2->next) {
       if (isdigit(ptr2->next->data))
         break ;
       ptr2 = ptr2->next ;
     }
     ptr1 = head ;
     while (ptr1) {
       temp = ptr2->next->next ;
       ptr2->next->next = ptr1->next ;
       ptr1->next = ptr2->next ;
       ptr2->next = temp ;
       ptr1 = ptr1->next->next ;
     }
     return head ;
   }
   
   int main() {
     node* head ;
     head = getData () ;
     printf ( "\nPrinting the list\n" ) ;
     printList (head);
     printf ( "\nBefore operation\n" ) ;
     head = performOperation (head) ;
     printf ( "\nAfter operation\n") ;
     printList (head);
     return 0 ;
   }

Reply

You must log in to post.

RSS feed for this topic