Remove Duplicates from Sorted List

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

Time: O(n)

Space: O(1)