DATA STRUCTURES IN C – LINKED LIST (20 PROGRAMS)

Linked List in C- Reversing Every N Nodes of Linked List using Recursion :

Input: 1->2->3->4->5->6->7->8
Output: 3->2->1->6->5->4->8->7

Source Code :

#include<stdio.h>
struct node
{
    	int data;
    	struct node *next;
};

struct node* reverse(struct node **head,int N)
{
    	struct node *next;
    	struct node *prev=NULL;	
    	struct node *cur=*head;
    	int i=1;

    	struct node *holder=*head;

    	while(cur!=NULL && i<=N)
    	{
        		next=cur->next;
        		cur->next=prev;		
        		prev=cur;		
        		cur=next;
        		i++;			
    	}
    if(next!=NULL)
    {
        		holder->next = reverse(&next,N); 
    	}
    return prev;
}

void print(struct node **head)
{
    	struct node *temp=*head;
    	printf("\nList:");
	    while(temp!=NULL)
    	{
        		printf("\n%d ",temp->data);
        		temp=temp->next;		
    	}
}

int main()
{
    	struct node *one = (struct node*)malloc(sizeof(struct node));
    	struct node *two = (struct node*)malloc(sizeof(struct node));
    	struct node *three = (struct node*)malloc(sizeof(struct node));
    	struct node *four = (struct node*)malloc(sizeof(struct node));
    	struct node *five = (struct node*)malloc(sizeof(struct node));
    	struct node *six = (struct node*)malloc(sizeof(struct node));
    	struct node *seven = (struct node*)malloc(sizeof(struct node));
    	struct node *eight = (struct node*)malloc(sizeof(struct node));

    	struct node *head=one;

    	one->data=1;
    	one->next=two;

    	two->data=2;	
    	two->next=three;

    	three->data=3;
    	three->next=four;

    	four->data=4;
    	four->next=five;

    	five->data=5;	
    	five->next=six;

    	six->data=6;
    	six->next=seven;

    	seven->data=7;
    	seven->next=eight;

    	eight->data=8;
    	eight->next=NULL;

    	printf("\nBefore Reversing:");
    	printf("\nLinked List:");
    	print(&head);

    	head=reverse(&head,3);

    	printf("\nAfter Reversing:");
    	printf("\nLinked List:");
    	print(&head);	

    	return 0;
}

Output :

Before Reversing:
Linked List:
List:
1
2
3
4
5
6
7
8

After Reversing:
Linked List:
List:
3
2
1
6
5
4
8
7