initial: 0  5  2  2  7  3  7  9  0  2
 ought2b: 0  0  2  2  2  2  0  0  2  2
outcome: 0  0  2  2  2  2  0  0  2  2

initial: 0
 ought2b: 0  0

initial: 1
 ought2b: (empty)

void RemOddDupEven(Node*& headPtr){
    // Define two cursors to iterate through referenced list.
    Node *precursor = 0,
            *cursor = headPtr;

    // Error Checking | Check for reference to empty list.
    if(headPtr == 0){
        cerr << "RemOddDupEven() attempted on empty list" << endl;
        return;
    }

    while(cursor->link != 0){
        if(cursor->data%2 != 0){
            /// Odd node found in referenced list. Remove it.
            if(precursor == 0){
                // No previous. Removing first node.
                precursor = cursor;
                cursor = cursor->link;
                headPtr = cursor;
                delete precursor;
                precursor = 0;
            } else {
                Node* tempNodePtr = cursor;
                cursor = cursor->link;
                precursor->link = cursor;
                delete tempNodePtr;
            }
        } else {
            /// Even node found in referenced list. Duplicate it.
            if(precursor == 0){
                // No previous. Duplicate and insert before current node.
                Node* newNodePtr = new Node;
                newNodePtr->data = cursor->data;
                newNodePtr->link = cursor;
                headPtr = newNodePtr;
                precursor = cursor;
                cursor = cursor->link;
            } else {
                // There is a previous. Duplicate and insert before current.
                Node* newNodePtr = new Node;
                newNodePtr->data = cursor->data;
                precursor->link = newNodePtr;
                newNodePtr->link = cursor;
                precursor = cursor;
                cursor = cursor->link;
            }
        }

    }
    /// We are at last item in the list.
    if(cursor->data%2 != 0){
        /// Odd node found at end of referenced list. Remove it.
        precursor->link = 0;
        delete cursor;
        cursor = 0;
    } else {
        /// Even node found at the end of referenced list. Duplicte it.
        Node* newNodePtr = new Node;
        newNodePtr->data = cursor->data;
        precursor->link = newNodePtr;
        newNodePtr->link = cursor;
    }
}