Remove duplicates from a sorted linked list.cpp

/* C++ Program to remove duplicates from a sorted linked list */
#include <bits/stdc++.h>
using namespace std;

/* Link list node */
class Node
{
	public:
	int data;
	Node* next;
};

/* The function removes duplicates from a sorted list */
void removeDuplicates(Node* head)
{
	/* Pointer to traverse the linked list */
	Node* current = head;

	/* Pointer to store the next pointer of a node to be deleted*/
	Node* next_next;
	
	/* do nothing if the list is empty */
	if (current == NULL)
	return;

	/* Traverse the list till last node */
	while (current->next != NULL)
	{
	/* Compare current node with next node */
	if (current->data == current->next->data)
	{
		/* The sequence of steps is important*/		
		next_next = current->next->next;
		free(current->next);
		current->next = next_next;
	}
	else /* This is tricky: only advance if no deletion */
	{
		current = current->next;
	}
	}
}

/* UTILITY FUNCTIONS */
/* Function to insert a node at the beginning of the linked list */
void push(Node** head_ref, int new_data)
{
	/* allocate node */
	Node* new_node = new Node();
			
	/* put in the data */
	new_node->data = new_data;
				
	/* link the old list off the new node */
	new_node->next = (*head_ref);	
		
	/* move the head to point to the new node */
	(*head_ref) = new_node;
}

/* Function to print nodes in a given linked list */
void printList(Node *node)
{
	while (node!=NULL)
	{
		cout<<" "<<node->data;
		node = node->next;
	}
}

/* Driver program to test above functions*/
int main()
{
	/* Start with the empty list */
	Node* head = NULL;
	
	/* Let us create a sorted linked list to test the functions
	Created linked list will be 11->11->11->13->13->20 */
	push(&head, 20);
	push(&head, 13);
	push(&head, 13);
	push(&head, 11);
	push(&head, 11);
	push(&head, 11);									

	cout<<"Linked list before duplicate removal ";
	printList(head);

	/* Remove duplicates from linked list */
	removeDuplicates(head);

	cout<<"\nLinked list after duplicate removal ";	
	printList(head);			
	
	return 0;
}