Remove Duplicates from Sorted List — Single Pass

// C++
ListNode* deleteDuplicates(ListNode* head) {
    ListNode* cur = head;
    while (cur && cur->next) {
        if (cur->val == cur->next->val) cur->next = cur->next->next;
        else cur = cur->next;
    }
    return head;
}

// Java
public ListNode deleteDuplicates(ListNode head) {
    ListNode cur = head;
    while (cur != null && cur.next != null) {
        if (cur.val == cur.next.val) cur.next = cur.next.next;
        else cur = cur.next;
    }
    return head;
}

# Python
def deleteDuplicates(head):
    cur = head
    while cur and cur.next:
        if cur.val == cur.next.val: cur.next = cur.next.next
        else: cur = cur.next
    return head