public class RemoveDuplicatesFromSortedList {
    /**
     * @param ListNode head is the head of the linked list
     * @return: ListNode head of linked list
     */
    public static ListNode deleteDuplicates(ListNode head) {
        if (head == null || head.next == null) return head;

        ListNode curr = head;
        while (curr != null && curr.next != null) {
            if (curr.val == curr.next.val) {
                curr.next = curr.next.next;
            } else {
                curr = curr.next;
            }
        }

        return head;
    }
}

Add one more easy level linked list problem.