remove all nodes with same value in a linked list

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,

Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

The following is my code:

ListNode *getNextElement(ListNode *head, bool& repeated){   
    while ((head->next) != NULL &&
            (head->val == head->next->val)){        
        head = head->next;
        repeated = true;            
    }

    return head->next;
}

ListNode *deleteDuplicates(ListNode *head) {
    ListNode *result = NULL;
    ListNode *copy_result = result;
    ListNode *next = NULL;

    for (ListNode *cur = head; cur != NULL; cur = next){
        bool cur_repeat = false;
        next = getNextElement(cur, cur_repeat);

        if (cur_repeat == true){
            while(cur!=next){
                ListNode *toFree = cur;
                cur = cur->next;
                delete toFree;
            }
        }
        else{
            if(result == NULL){
                result = cur;
                copy_result = result;
            }
            else{
                result->next = cur;
                result = result->next;
            }           
        }
    }

    if(result != NULL)
        result->next = NULL;
    return copy_result;
}