18copyLastElmnt.c

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

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

void display(struct node**);
void createNode(struct node**);
void reverse(struct node**);
int count(struct node**);
void LLcopyLastnEl(struct node**,struct node**,int);
int main(){
	struct node *head=NULL;
	struct node *dest=NULL;
	int itr1,num,last;
	printf("Enter no. of nodes to be created.\n");
	scanf("%d",&num);
	for(itr1=0;itr1<num;itr1++){
		createNode(&head);	
	}
	printf("Input src Linked List: ");
	display(&head);
	reverse(&head);
	printf("\nEnter elements to be copied from last from src linked list: ");
	scanf("%d",&last);
	int cnt=count(&head);
	if(last<=cnt){
		
		LLcopyLastnEl(&head,&dest,last);
	}else{
		printf("\nYou are trying to copy elements which are not present.\n");
	}
	printf("\nOutput destination Linked List: ");
	display(&dest);
	return 0;
}
int count(struct node **head){
	struct node *temp=*head;
	int cnt=1;
	if(*head==NULL){
		return 0;
	}
	while(temp->next!=NULL){
		temp=temp->next;
		cnt++;
	}
	return cnt;
}
void LLcopyLastnEl(struct node **head,struct node **dest,int last){
	struct node *htemp=*head;
	int itr1;
	struct node *dtemp=*dest;
	struct node *newNode=NULL;
	for(itr1=0;itr1<last;itr1++){
		dtemp=*dest;
		if(htemp->next==NULL)
			break;
		newNode=(struct node*)malloc(sizeof(struct node));
		newNode->data=htemp->data;
		newNode->next=NULL;
		if(*dest==NULL){
			*dest=newNode;
		}else{
			while(dtemp->next!=NULL){
				dtemp=dtemp->next;
			}
			dtemp->next=newNode;
		}
		htemp=htemp->next;
	}
	reverse(dest);
}
void createNode(struct node **head){
	struct node *temp=*head;
	struct node *newNode;
	newNode=(struct node*)malloc(sizeof(struct node));
	printf("Enter data: ");
	scanf("%d",&newNode->data);
	newNode->next=NULL;
	if(*head==NULL){
		*head=newNode;
	}else{
		while(temp->next!=NULL){
			temp=temp->next;
		}
		temp->next=newNode;
	}
}
void display(struct node **head){
	struct node *temp=*head;
	while(temp->next!=NULL){
		printf("|%d|->",temp->data);
		temp=temp->next;
	}
	printf("|%d|",temp->data);
}
void reverse(struct node **head){
	struct node *first=*head;
	struct node *next1=*head;
	struct node *temp=NULL;
	while(first->next!=NULL){
		next1=first->next;
		first->next=temp;
		temp=first;
		first=next1;
	}
	first->next=temp;
	*head=first;	
}