Delete duplicate from list

PROBLEM :

Delete duplicate-value nodes from a sorted linked list

You're given the pointer to the head node of a sorted linked list, where the data in the nodes is in ascending order. Delete as few nodes as possible so that the list does not contain any value more than once. The given head pointer may be null indicating that the list is empty.
Input Format
You have to complete the Node* RemoveDuplicates(Node* head) method which takes one argument - the head of the sorted linked list. You should NOT read any input from stdin/console.

Output Format
Delete as few nodes as possible to ensure that no two nodes have the same data. Adjust the next pointers to ensure that the remaining nodes form a single sorted linked list. Then return the head of the sorted updated linked list. Do NOT print anything to stdout/console.

Sample Input

1 -> 1 -> 3 -> 3 -> 5 -> 6 -> NULL
NULL
Sample Output

1 -> 3 -> 5 -> 6 -> NULL
NULL

Explanation
1. 1 and 3 are repeated, and are deleted.
2. Empty list remains empty.

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SIMPLE c++ IMPLEMENTATION :
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/*
  Remove all duplicate elements from a sorted linked list
  Node is defined as
  struct Node
  {
     int data;
     struct Node *next;
  }
*/
struct Node* RemoveDuplicates(struct Node *head)
{
   struct Node *temp ,*ptr ;
    temp=head ;
    if(head==NULL) return NULL ;
 
    while(head->next&&head->data==head->next->data)
        {
        ptr=head ;
        head=head->next ;
        free(ptr) ;
    }
 
    while(temp!=NULL&&temp->next!=NULL&&temp->next->next!=NULL)
        {
        if(temp->next->data==temp->next->next->data)
            {
            ptr=temp->next ;
            temp->next=ptr->next ;
            free(ptr) ;
        }
        temp=temp->next ;
    }
 
    return head ;
}

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