<![CDATA[
CSE142 Final
Spring 2016
Name of Student_______________________________________________________________
Section (e.g., AA)___________________ TA_____________________________________
This exam is divided into eleven questions with the following points:
# Problem Area Points Score
-----------------------------------------------------
1 Reference Mystery 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 _____
This is a closed-book/closed-note exam. Space is provided for your answers.
There is a "cheat sheet" at the end that you can use as scratch paper or to
write answers. You can also request scratch paper from a TA. You are not
allowed to access any of your own papers during the exam.
In general the exam is not graded on style and you do not need to include
comments, although the Critter class has special requirements you must follow.
You are limited to the constructs described in chapters 1 through 10 of the
textbook, which means that you are not allowed to use break statements or to
have a return from a void method. You are not allowed to use methods from the
Arrays class or other methods that aren't included on the cheat sheet. 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. 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. Reference Mystery, 5 points. What output is produced by this program?
import java.util.*;
public class ReferenceMystery {
public static void main(String[] args) {
int x = 1;
int y = 7;
int[] data = {2, 4, 6};
mystery1(data[x], data);
System.out.println(x + " " + Arrays.toString(data));
x = mystery2(x, y);
System.out.println(x + " " + y);
}
public static void mystery1(int z, int[] numbers) {
z = z + 3;
numbers[z / 3]++;
z = 3;
numbers[z - 2]--;
System.out.println(z + " " + Arrays.toString(numbers));
}
public static int mystery2(int x, int y) {
y++;
x = x + y;
return x + y;
}
}
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 = 2; i < list.length; i++) {
if (i >= list[i - 1]) {
list[i] = list[i - 1] * 2 + 1;
}
}
}
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
-----------------------------------------------------------------
{0, 2, 3} _________________________________
{1, 1, 4, 5} _________________________________
{3, 1, 2, 9, 5} _________________________________
{5, 1, 1, 1, 8} _________________________________
{2, 1, 1, 2, 3, 4} _________________________________
3. Inheritance, 6 points. Assume the following classes have been defined:
public class A extends B {
public String toString() {
return "a";
}
}
public class B extends D {
public void method1() {
System.out.println("b 1");
}
public void method2() {
System.out.println("b 2");
}
}
public class C extends D {
public void method1() {
System.out.println("c 1");
}
}
public class D {
public String toString() {
return "d";
}
public void method1() {
System.out.println("d 1");
}
public void method2() {
System.out.println("d 2");
}
}
Consider the following code fragment:
D[] elements = {new B(), new A(), new D(), new C()};
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? Write the output as a series of
3-line columns in order from left to right (do not label columns or rows).
4. Token-Based File Processing, 10 points. Write a static method called
tallyScores that takes as a parameter a Scanner containing a series of
student records and that prints a summary of each student record. A student
record will begin with a name followed by a sequence of integer tests
scores. The name is guaranteed to be one word composed of letters. You
may assume that each student has at least one test score. Your method
should produce two lines of output for each student: one showing the
student's name and test scores and a second line showing the average score.
For example, if a Scanner called records contains the following:
John 71 83 94 Sally 94
85 Fred 90 95 82 85
and the following call is made:
tallyScores(records);
the following output should be produced:
John: 71 83 94
average = 82.66666666666667
Sally: 94 85
average = 89.5
Fred: 90 95 82 85
average = 88.0
You are to exactly reproduce the format of this output. Notice that line
breaks in the input are not meaningful and that the average score is not
rounded. You may not construct any extra data structures to solve this
problem.
5. Line-Based File Processing, 9 points. Write a static method called
switchNames that takes a Scanner containing an input file as a parameter and
that echoes the input to System.out with names switched in order. More
specifically, the input file will contain lines that have the text "name:".
Each such line will be followed by a line that has a name in the form of a
last name followed by a comma and exactly one space followed by a first
name. Your program should produce one line of output for each such pair of
input lines with the first name followed by the last name and a space in
between. For example, if a Scanner called input contains this text:
As we discussed, these are the students to discuss at the meeting:
name:
Von Trapp, Maria
name:
Thornton, Billy Bob
If there is time, we should also discuss:
name:
Porter, Riley
name:
Reges, Stuart
Then the call:
switchNames(input);
should produce the following output:
As we discussed, these are the students to discuss at the meeting:
Maria Von Trapp
Billy Bob Thornton
If there is time, we should also discuss:
Riley Porter
Stuart Reges
You may not construct any extra data structures to solve this problem other
than strings.
6. Arrays, 10 points. Write a static method called minGap that takes an array
of integers as a parameter and that returns the minimum gap between adjacent
values in the array. The gap between two adjacent values in a list is
defined as the second value minus the first value. Consider a variable
called list defined as follows:
int[] list = {1, 3, 6, 7, 12};
The first gap is 2 (3 - 1), the second gap is 3 (6 - 3), the third gap is 1
(7 - 6) and the fourth gap is 5 (12 - 7). Thus, the call:
minGap(list)
should return 1 because that is the smallest gap in the list. Notice that
the minimum gap could be a negative number. If the list has fewer than 2
elements, your method should return 0. Below are several examples of what
value would be returned for a given array.
Array passed as parameter Value Returned
-------------------------------------- --------------
{} 0
{8} 0
{4, 17} 13
{3, 5, 11, 4, 8} -7
{2, 8, 8, 10, 15} 0
You may not construct any extra data structures to solve this problem and
your method should not alter the array passed as a parameter.
7. ArrayList, 10 points. Write a static method called cloneOddsRemoveEvens
that takes an ArrayList of integer values as a parameter and that replaces
each odd number with two of that number and that removes all even values.
For example, suppose that a variable called list stores the following
sequence of values:
[3, 8, 19, 42, 7, 26, 27, -8, 193, 204, 6, -4]
and we make the following call:
cloneOddsRemoveEvens(list);
Afterwards the list should store the following sequence of values:
[3, 3, 19, 19, 7, 7, 27, 27, 193, 193]
Notice that each odd number has been duplicated (3, 19, 7, 27, 193) and that
the even values have been removed (8, 42, 26, -8, 204, 6, -4). Below are
several examples of how an ArrayList should be changed by the method.
ArrayList contents before call ArrayList contents after call
------------------------------ ------------------------------
[] []
[82] []
[3, 8, 15] [3, 3, 15, 15]
[2, 4, 6, 8] []
[17, 5, 3, 9] [17, 17, 5, 5, 3, 3, 9, 9]
[1, 2, 3, 4, 5, 6] [1, 1, 3, 3, 5, 5]
You may not construct any extra data structures to solve this problem. You
must solve it by manipulating the ArrayList you are passed as a parameter.
See the cheat sheet for a list of available ArrayList methods.
8. Critters, 15 points. Write a class called Spider that extends the Critter
class. The instances of the Spider class alternate between "north" mode in
which they are trying to travel north and "south" mode in which they are
trying to travel south. Each spider should start out in north mode.
Spiders always infect when an enemy is in front of them. Otherwise they
turn left if they are not facing in the desired direction. If there is no
enemy in front and they are facing in the desired direction, they hop if
possible. When they are unable to hop in the desired direction, they switch
to the other mode. Spiders are always green and their display string is
composed of either "N-" or "S-" depending upon whether they are in north or
south mode followed by the number of hops they have successfully made in
that direction since they last switched. For example, each spider will
initially display as "N-0" indicating that they are trying to move north but
haven't yet made any moves. If they are able to move north, their display
becomes "N-1", "N-2", and so on, until they switch to south mode, at which
time they display as "S-0", and so on.
As in assignment 8, fields must be declared private, fields initialized to a
non-default value must be set in a constructor, and all updates to fields
must occur in the getMove method.
9. Arrays, 15 points. Write a static method called insert that takes two
arrays of integers and an integer index as parameters and that returns a new
array that contains the result of inserting the values from the second array
into the first array starting at the specified index. For example if the
variables list1 and list2 contain the following values:
list1: [7, 2, 8, 9, 4, 13, 7, 1, 9, 10] list2: [1, 2, 3, 4, 5]
Then the call insert(list1, list2, 2) should return a new array that stores:
[7, 2, 1, 2, 3, 4, 5, 8, 9, 4, 13, 7, 1, 9, 10]
| |
+---list2---+
Notice that the new array has all of the values from list1 in their original
order, but starting at index 2 the new array has the five values from list2.
The order of the parameters matters. For example, insert(list2, list1, 3)
should produce the following array as its result:
[1, 2, 3, 7, 2, 8, 9, 4, 13, 7, 1, 9, 10, 4, 5]
| |
+-----------list1------------+
You may assume that the index passed as a parameter is legal (between 0 and
the length of the array passed as the first parameter).
Your method should not construct any extra data structures other than the
array to be returned and it should not alter its two array parameters. You
are not allowed to call methods of the Arrays class to solve this problem.
10. Programming, 10 points. Write a static method called samePattern that
returns true or false depending upon whether two strings have the same
pattern of characters. More precisely, two strings have the same pattern
if they are of the same length and if two characters in the first string
are equal if and only if the characters in the corresponding positions in
the second string are also equal. Below are some examples of patterns that
are the same and patterns that differ (keep in mind that the method should
return the same value no matter what order the two strings are passed).
1st String 2nd String Same Pattern?
------------ -------------- -------------
"" "" true
"a" "x" true
"a" "ab" false
"ab" "ab" true
"aa" "xy" false
"aba" "+-+" true
"---" "aba" false
"abcabc" "zodzod" true
"abcabd" "zodzoe" true
"abcabc" "xxxxxx" false
"aaassscccn" "aaabbbcccd" true
"asasasasas" "xyxyxyxyxy" true
"ascneencsa" "aeiouuoiea" true
"aaassscccn" "aaabbbcccd" true
"asasasasas" "xxxxxyyyyy" false
"ascneencsa" "aeiouaeiou" false
"aaassscccn" "xxxyyyzzzz" false
"aaasssiiii" "gggdddfffh" false
Your method should take two parameters: the two strings to compare. You
are allowed to create new strings, but otherwise you are not allowed to
construct extra data structures to solve this problem (no array, ArrayList,
Scanner, etc). You are limited to the string methods on the cheat sheet.
11. Art, 1 point (bonus). You've programmed lions, bears, giants, and huskies,
but what kind of critter would your TA be? Give an artistic rendering of
how you see your TA fitting into the unforgiving world of the critter
simulation. 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.
]]>
Stuart Reges
Last modified: Fri Sep 16 16:16:07 PDT 2011