Random Quiz #7

CPS 100, Spring 1997

Due: March 10

Problem 1: 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 != 0) { Node * first; Node * second; SplitList(list,first,second); MergeSort(first); MergeSort(second); list = Merge(first,second); } } Part A ( 2 points)

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

Part B ( 2 points)

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

Part C ( 2 points) If SplitList and Merge execute in O(n) time for a list of n elements, what is the complexity of the implementation of MergeSort above? Why?

Part D ( 2 points)

The code below is the body of an implementation of SplitList. Add statement(s) as needed to make it work properly.

{ if (list != 0) { first = list; Node * temp = list; second = list; while (temp->next != 0) { temp = temp->next->next; second = second->next; } // statement needed here } }

Problem 2 : Canine Order (2 points)

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).

Problem 3: Hash, Hash, and more Hash (3 points)

Suppose integers are being inserted into a hashtable of 11 elements. The integers are hashed using the hash function below. int Hash(int n) { return (n*2) + n/2; } The values returned by Hash are converted to indices in the hash table by using %11 (the remainder after dividing by 11). Hash collisions are resolved using chaining and new elements are inserted at the front of each linked list.

Draw a diagram of the hash table that results from inserting

5, 22, 17, 18, 35, 101, 16, 0, 8

into the hash htable in the order shown (5 first, 8 last)

Owen L. Astrachan

Last modified: Mon Oct 27 14:04:36 EST 1997