delduplicate.java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head==null || head.next==null)
        { 
           return head;
        }
        ListNode curr= head.next;
        ListNode prev= head;
        while(curr!= null)
        {
            if(prev.val == curr.val)
            {
                curr=curr.next;
            }
           else 
            
            {
                prev.next=curr;
                prev=curr;
                curr=prev.next;
            }
        }
        prev.next=null;
        return head;
        }
    }