<![CDATA[
CSE142 Final
Winter 2009
Name of Student_______________________________________________________________
Section (e.g., AA)___________________ TA_____________________________________
This is an open-book/open-note exam. Space is provided for your answers. Use
the backs of pages if necessary. The exam is divided into eleven questions
with the following points:
# Problem Area Points Score
-----------------------------------------------------
1 Expressions 5 _____
2 Array Simulation 10 _____
3 Inheritance 6 _____
4 Token-Based File processing 10 _____
5 Line-Based File Processing 9 _____
6 Arrays 10 _____
7 ArrayList 10 _____
8 Critters 15 _____
9 Arrays 15 _____
10 Programming 10 _____
11 Art (bonus) 1 _____
----------------------------------
Total 100 _____
In general the exam is not graded on style and you do not need to include
comments, although all fields of a class should be declared private. You do
not have to include any import statements. Do not abbreviate any code that you
write (e.g., S.o.p versus System.out.print) and do not abbreviate any answer
asking for sample output (show the complete output).
You are NOT to use any electronic devices while taking the test, including
calculators. Anyone caught using an electronic device will receive a 10 point
penalty.
Do not begin work on this exam until instructed to do so. Any student who
starts early or who continues to work after time is called will receive a 10
point penalty.
If you finish the exam early, please hand your exam to the instructor and exit
quietly through the front door.
1. Expressions, 5 points. For each expression in the left-hand column,
indicate its value in the right-hand column. Be sure to list a constant of
appropriate type (e.g., 7.0 rather than 7 for a double, Strings in quotes).
Expression Value
8.0/4/4 + 3/4 + 0.5 * 3 __________
88 % 10 % 5/2 + 7 % 8 __________
2 * 3 + 4 + " = " + 5 * 6 + 7 __________
54/5/2.0/4 * 3 __________
2 * (0.75 + 1.25)/5 * 10 - 7/4 __________
2. Array Simulation, 10 points. You are to simulate the execution of a method
that manipulates an array of integers. Consider the following method:
public static void mystery(int[] list) {
for (int i = 0; i < list.length - 1; i++) {
if (i % 2 == 0) {
list[i]++;
} else {
list[i]--;
}
}
}
In the left-hand column below are specific lists of integers. You are to
indicate in the right-hand column what values would be stored in the list
after method mystery executes if the integer list in the left-hand column
is passed as a parameter to mystery.
Original List Final List
------------------------------------------------------------
{6, 3} ____________________________
{2, 4, 6} ____________________________
{1, 2, 3, 4} ____________________________
{2, 2, 2, 2, 2} ____________________________
{7, 3, 2, 0, 5, 1} ____________________________
3. Inheritance, 6 points. Assume the following classes have been defined:
public class D extends C {
public String toString() {
return "d";
}
public void method2() {
System.out.println("d 2");
}
}
public class B {
public String toString() {
return "b";
}
public void method1() {
System.out.println("b 1");
}
public void method2() {
System.out.println("b 2");
}
}
public class A extends D {
public String toString() {
return "a";
}
}
public class C extends B {
public void method1() {
System.out.println("c 1");
}
}
Consider the following code fragment:
B[] elements = {new C(), new A(), new D(), new B()};
for (int i = 0; i < elements.length; i++) {
System.out.println(elements[i]);
elements[i].method1();
elements[i].method2();
System.out.println();
}
What output is produced by this code?
4. Token-Based File Processing, 10 points. Write a static method called
evaluate that takes as a parameter a Scanner containing a series of tokens
that represent a numeric expression involving addition and subtraction and
that returns the value of the expression. For example, if a Scanner called
data contains the following tokens:
4.2 + 3.4 - 4.1
and we make the following call:
evaluate(data)
the method should evaluate the result as (4.2+3.4-4.1) = (7.6-4.1) = 3.5 and
should return this value as its result. Every expression will begin with a
real number and then will have a series of operator/number pairs that
follow. The operators will be either "+" (addition) or "-" (subtraction).
As in the example above, there will be spaces separating numbers and
operators. You may assume the expression is legal.
Your program should evaluate operators sequentially from left to right. For
example, for this expression:
7.3 - 4.1 - 2.0
your method should evaluate the operators as follows:
7.3 - 4.1 - 2.0 = (7.3 - 4.1) - 2.0 = 3.2 - 2.0 = 1.2
The Scanner might contain just a number, in which case your method should
return that number as its result.
5. Line-Based File Processing, 9 points. Write a static method called
processScores that takes as a parameter a Scanner containing a series of
lines that represent student records. Each student record takes up two
lines of input. The first line has the student's name and the second line
has a series of plus and minus characters. Below is a sample input:
Kane, Erica
--+-+
Chandler, Adam
++-+
Martin, Jake
+++++++
Dillon, Amanda
++-++-+-
The number of plus/minus characters will vary, but you may assume that at
least one such character appears and that no other characters appear on the
second line of each pair.
For each student you should produce a line of output with the student's name
followed by a colon followed by the percent of plus characters. For
example, if the input above is stored in a Scanner called input and we make
the following call:
processScores(input);
The following output should be produced:
Kane, Erica: 40.0% plus
Chandler, Adam: 75.0% plus
Martin, Jake: 100.0% plus
Dillon, Amanda: 62.5% plus
You must exactly reproduce this format.
6. Arrays, 10 points. Write a static method called isFibLike that takes an
array of integers as a parameter and that returns whether or not the
sequence matches the pattern of the Fibonacci sequence (true if it does,
false if it does not). The Fibonacci sequence begins with the number 1
followed by the number 1 and each successive value is the sum of the two
previous values: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, and so on.
It is possible to follows this pattern with different starting values. For
example, Lucas numbers start with the values 2 and 1 but otherwise follow
the Fibonacci pattern.
Your method should determine whether each value after the first two is the
sum of the previous two values in the sequence, returning true if the
sequence has that pattern and returning false if it does not. If the array
has two or fewer values, your method should return true. Below are sample
arrays and the value that should be returned for each:
Contents of Array Value returned
passed to isFibLike by isFibLike
--------------------------- --------------
{} true
{42} true
{18, 42} true
{1, 1, 1} false
{1, 2, 3} true
{0, 0, 0, 0, 0} true
{1, 1, 2, 3, 5, 8, 13, 21} true
{2, 1, 3, 4, 7, 11, 18, 29} true
{1, 1, 2, 3, 5, 12, 17} false
7. ArrayList, 10 points. Write a static method called reverse3 that takes an
ArrayList of integer values as a parameter and that reverses each successive
sequence of three values in the list. For example, suppose that a variable
called list stores the following sequence of values:
[3, 8, 19, 42, 7, 26, 19, -8, 193, 204, 6, -4]
and we make the following call:
reverse3(list);
Afterwards the list should store the following sequence of values:
[19, 8, 3, 26, 7, 42, 193, -8, 19, -4, 6, 204]
The first sequence of three values (3, 8, 19) has been reversed to be (19,
8, 3). The second sequence of three values (42, 7, 26) has been reversed to
be (26, 7, 42). And so on. If the list has extra values that are not part
of a sequence of three, those values are unchanged. For example, if the
list had instead stored:
[3, 8, 19, 42, 7, 26, 19, -8, 193, 204, 6, -4, 99, 2]
The result would have been:
[19, 8, 3, 26, 7, 42, 193, -8, 19, -4, 6, 204, 99, 2]
Notice that the values (99, 2) are unchanged in position because they were
not part of a sequence of three values. Recall that the primary methods for
manipulating an ArrayList<E> are:
add(E value) appends value at end of list
add(int index, E value) inserts given value at given index, shifting
subsequent values right
clear() removes all elements of the list
get(int index) returns the value at given index
remove(int index) removes and returns value at given index,
shifting subsequent values left
set(int index, E value) replaces value at given index with given value
size() returns the number of elements in list
8. Critters, 15 points. Write a class called Orca that extends the Critter
class. The instances of the Orca class follow a pattern of moving forward
four times, then turning around, then moving back four times and turning
around again so that they return to their original position and direction.
Each Orca is always either in moving-mode or in turning-mode. They start
out in moving-mode. While in moving-mode, they try to hop forward if
possible until they have hopped four times, at which point they switch into
turning-mode. If it is not possible to hop while in moving-mode, an Orca
instead infects whatever is in front of it. When in turning-mode, the Orca
turns left twice and then switches back to moving-mode. Don't worry about
the fact that if the Orca encounters a wall while in moving-mode, it gets
stuck trying to infect the wall indefinitely. The Orca displays itself as
"M" while in moving-mode and as "T" while in turning-mode. Its color should
be the default color for critters.
9. Arrays, 15 points. Write a static method called append that takes two
integer arrays as parameters and that returns a new array that contains the
result of appending the values of the second array at the end of the first
array. For example, suppose that arrays list1 and list2 have been declared
as follows:
int[] list1 = {2, 4, 6};
int[] list2 = {1, 2, 3, 4, 5};
If we make the following call:
append(list1, list2)
The method will return a new array that contains the following values:
[2, 4, 6, 1, 2, 3, 4, 5]
If the call instead had been:
append(list2, list1)
Then the method would return a new array that contains:
[1, 2, 3, 4, 5, 2, 4, 6]
Your method should not change either of the arrays passed as parameters.
10. Programming, 10 points. Write a static method called acronym that takes as
a parameter a String containing a phrase and that returns an acronym for
the phrase. For example, the following call:
acronym("self-contained underwater breathing apparatus")
should return "SCUBA". The acronym is formed by combining the capitalized
first letters of each word in the phrase. Words in the phrase will be
separated by some combination of dashes and spaces. There might be extra
spaces or dashes at the beginning or end of the phrase. The String will
not contain any characters other than dashes, spaces, and letters, and is
guaranteed to contain at least one word. Below are several sample calls.
Method Call Value Returned
----------------------------------------------- --------------
acronym(" automatic teller machine ") "ATM"
acronym("personal identification number") "PIN"
acronym("computer science") "CS"
acronym("merry-go-round") "MGR"
acronym("All my Children") "AMC"
acronym("Troubled Assets Relief Program") "TARP"
acronym("--quite-- confusing - punctuation-") "QCP"
acronym(" loner ") "L"
11. Art, 1 point (bonus). President Obama is busy filling cabinet positions.
Give an artistic rendering of how you see your TA fitting into the new
administration (Drug czar? Director of the CIA? Supreme Court Justice?).
You may either write a poem or draw a picture. If your answer below
indicates at least 1 minute of effort, you will receive full credit,
although your TA would probably appreciate it if you put in a little more
effort.
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Stuart Reges
Last modified: Fri Sep 16 16:06:48 PDT 2011