linkList_Basic.java

public class LinkedListUse {
	
	public static LinkedListNode<Integer> insertR(LinkedListNode<Integer> head, int data, int pos){
		
        if(pos == 0){
            LinkedListNode<Integer> newNode = new LinkedListNode<Integer>(data);
            newNode.next = head;
            return newNode;
        }
        
        if(head == null){
            return head;
        }
        
        head.next = insertR(head.next,data,pos-1);
        return head;
		
	}
	
	public static LinkedListNode<Integer> deleteNodeRec(LinkedListNode<Integer> head, int pos) {
    	
		
        if(pos == 0){
            
            return head.next;
        }
        
        if(head == null || head.next == null){
            return head;
        }
        
        head.next = deleteNodeRec(head.next,pos-1);
        return head;
		
	
	}

	public static Node<Integer> takeInput()
	{
		Node<Integer> head = null, tail = null;
		Scanner s = new Scanner(System.in);
		int data = s.nextInt();
				
		while(data != -1){
			Node<Integer> newNode = new Node<Integer>(data);
			if(head == null){
				head = newNode;
				tail = newNode;
			}else{
//				Node<Integer> temp = head;
//				while(temp.next != null){
//					temp = temp.next;
//				}
//				temp.next = newNode;
				tail.next = newNode;
				tail = newNode; // tail = tail.next
			}
			data = s.nextInt();
		}
		return head;
	}
	
	public static void print(Node<Integer> head){
		
		while(head != null){
			System.out.print(head.data +" ");
			head = head.next;
		}
		System.out.println();

	}
	
	public static LinkedListNode<Integer> deleteNode(LinkedListNode<Integer> head, int pos) {
		
		if(pos == 0){
			return head.next;
		}
		
        int i = 0;
		LinkedListNode<Integer> temp = head;
		while(i < pos - 1 && temp != null){
			temp = temp.next;
			i++;
		}
        
         if (temp == null || temp.next == null) 
            return head; 
        
         temp.next = temp.next.next;
		
		return head;
	}

	public static Node<Integer> insert(Node<Integer> head, int data, int pos){
		Node<Integer> newNode = new Node<Integer>(data);
		if(pos == 0){
			newNode.next = head;
			return newNode;
		}
		int i = 0;
		Node<Integer> temp = head;
		while(i < pos - 1){
			temp = temp.next;
			i++;
		}
		newNode.next = temp.next;
		temp.next = newNode;
		return head;
	}
	public static void main(String[] args) {
		Node<Integer> node1 = new Node<Integer>(10);
		Node<Integer> node2 = new Node<Integer>(20);
		Node<Integer> node3 = new Node<Integer>(30);
		node1.next = node2;
		node2.next = node3;
		Node<Integer> head = node1;
		print(head);
		print(head);
		

	}
	
	  private static LinkedListNode reverse(LinkedListNode<Integer> head){
     
       LinkedListNode current = head; 
       LinkedListNode next = null; 
       LinkedListNode prev = null; 
        while ( current != null)   
       { 
           next = current.next; 
           current.next = prev; 
           prev = current; 
           current = next; 
          
       } 
        
        return prev;
    }

}



public class Node<T> {
	
	T data;
	Node<T> next;
	
	Node(T data){
		this.data = data;
		next = null;
	}
	
}