1 what makes a program easy to modify2 describe

Question

1. What makes a program easy to modify?

2. Describe the order of magnitude of the following code section using Big(O) notation.

j = 1;

While (j < N)

{

  j = j * 2);

}

3. What are the benefits we accrue by using a Java interface construct to formally specify the logical level of ADTs?

4. Suppose we have a linked list of Strings, as defined in the textbook, named presidents. Suppose it contains three nodes, with the first node holding "Adams", the second node "Washington", and the third node "Kennedy". What would be output by the following code:

LLStringNode temp = presidents;

while (temp != null)

{

temp = temp.getLink();

}

System.out.println(temp.getInfo());

5. Suppose a collection object is defined to hold elements of class Object, and you use it to store String objects. Describe what you must do when you retrieve an object from the collection and intend to use it as a String.

6. Show what is written by the following segment of code, given that item1, item2, and item3 are int variables, and stack is an object that fits our abstract description of a stack. Assume that you can store and retrieve variables of type int on stack.

item1 = 1;

item2 = 0;

item3 = 4;

stack.push(item2);

stack.push(item1);

stack.push(item1 + item3);

item2 = stack.top();

stack.push (item3*item3);

stack.push(item2);

stack.push(3);

item1 = stack.top();

stack.pop();

System.out.println(item1 + " " + item2 + " " + item3);

while (!stack.isEmpty())

{

  item1 = stack.top();

stack.pop();

System.out.println(item1);

}

7. Explain the relationship between dynamic storage allocation and recursion.

8. Analyze the factorial method and answer the following questions:

int factorial (int n)

{

if (n > 0)

return (n * factorial (n - 1));

else

if (n == 0)

return 1;

}

a. What is the base case?

b. What is the general case?

c. What are the constraints on the argument values?

d. What does the method do?

9. What are the three interfaces we defined related to our Queue ADT?

10. Describe in general terms the approach we use to implement an unbounded queue based on an array.

11.  What does it mean for a class's equals and compareTo methods to be "consistent"?

12.  Questions a-e below refer to the following figure:

a. What are the ancestors of node J?

b. What are the descendants of node T?

c. What are the descendants of node B?

d. What is the order in which the nodes are visited by a preorder traversal?

e. What is the order in which the nodes are visited by a postorder traversal?

13.  If a heap is used to implement a priority queue, what is the big O efficiency of the enqueue operation, assuming the size of the priority queue is N?

14.  What would be the order of the following list after two iterations of the "inner" part of the Insertion Sort algorithm?

13         4          16         19         2          15         12         3          23         20

15.  Suppose we are using Merge Sort to sort the following list of numbers. What would be the order of the list immediately before the execution of the merge method in the original (non-recursive) call to mergesort?

13         4          16         19         2          15         12         3          23         20

16.  Programming Sorting Algorithms: For this section, use the Sorts.java test harness.

a. Describe an approach to modifying the Sorts.java program so that after calling a sorting method the program prints out the number of swaps needed by the sorting method.

b. Implement your approach.

c. Test your new program by running the selectionSort method. Your program should report 49 swaps.

d. Now, modify your program to also output the number of comparisons (compares) needed. You must include one or more statements to increment your counter within the sorting methods themselves. For each of the listed methods, make and test the changes needed, and list both the number of swaps and the number of compares needed by the Sorts program to sort an array of 50 random integers.

selectionSort     swaps:____       compares:____

bubbleSort        swaps:____       compares:____

shortBubble      swaps:____       compares:____

insertionSort     swaps:____       compares:____