Name: _____________________________________

Honor Code Acknowledgment: _________________


                      Random Quiz  9  
                    CPS 100, Fall 1994 
                     November 7, 1994





Problem: Sorting with John Barleycorn

Consider the following code for implementing a merge sort of two linked
lists.


    void MergeSort(Node * & list)
    // postcondition: list is sorted in non-decreasing order
    {    
        if (list != NULL) {
            Node * first;
            Node * second;
            SplitList(list,first,second);
            MergeSort(first);
            MergeSort(second);
            list = Merge(first,second);
        }
     }   
    

part A:

Does list need to be reference parameter?  why/why not





part B:

Write the function prototype/header for the function SplitList so
that the function MergeSort above will work as intended.




part C:

If SplitList executes in O(n) time for a list of n elements, what is the
complexity of the implementation of MergeSort above?  Why?






part D:

If first has  m elements and second has n  elements,
what is the complexity of Merge(first,second) (assuming a
good implementation)?  Why?






part E:

The code below is the body of an implementation of SplitList.
Add a statement(s) as needed to make it work properly.
   
       if (list != NULL) {
           first = list;
           Node * temp = list;
           second = list;
           while (temp->next != NULL) {
               temp = temp->next->next;
               second = second->next;
           }
           // statement needed here


       
   
        }

Canine Order

True or False:  It never makes sense to use an  O(n^2) sort since 
O(n log n)  sorts exist.  Justify your answer (briefly).