Lab 4: Loops
Download and unzip lab4.zip, which contains all
the files you will need for this assignment. Open the
file Lab4.java in DrJava. All the code you write for this
assignment should be added to this file. Note that some useful methods
have already been implemented for you.
In each exercise, you will be given a task for the robot to
complete. It does not matter where the robot ends up at the completion
of the task, as long as the appropriate squares have changed color. To
receive full credit, your program must complete the task and
terminate without any errors. As always, you should aim to minimize duplicate code in your solutions.
Exercise 1: completeBars
In this exercise, the robot initially finds itself on a map like the
one shown in the example below.
Each column initially contains exactly one dark square. Complete
the completeBars method, which should darken all the squares
in each column that are below the original dark square. After calling
the completeBars method on the example shown above, the map
should appear as follows:
You should assume that the robot will always start in the southwest
corner facing east, that there will be exactly one dark square per
column, and that there will be no walls on the map. You should not
make any assumptions about the dimensions of the map, or about the
position of the dark squares within each column.
Be sure to test your code on both "bars1.txt" and "bars2.txt".
(For your convenience you may use the testCompleteBars1 and
testCompleteBars2 methods to test your code on these maps.)
Exercise 2: combinePiles
In this exercise, there are initially two piles of dark squares, one
at the bottom of each column, as shown in the example below (lefthand
picture).
| Before combinePiles: |
After combinePiles: |
 |
 |
Complete the combinePiles method, which should move all dark
squares from the left pile to the top of the right pile. After
calling the combinePiles method on the example shown in the
lefthand picture above, the map should appear as shown in the
righthand picture.
Hint: Move one dark square at a time, from the left column to the
right column.
You should assume that the robot will always start in the southwest
corner facing north, that there will always be exactly 2 columns, and
that each column contains a pile of zero or more (contiguous) dark
squares. There will never be any walls on the map. A pile of dark
squares may fill an entire column, or there may be light squares above
the pile. There will always be at least enough room in the right
column to add all the darks from the left pile (but there may be
exactly enough room). You should not make any assumptions about the
number of rows in the map, or the heights of the 2 piles.
Be sure to test your code on both "piles1.txt" and "piles2.txt".
Exercise 3: connectDots
In this exercise, the robot initially finds itself at the beginning of
a dotted path, like the one shown in the example below.
There will always be exactly one light square between each dot.
Complete the connectDots method, which should darken squares
to connect the dots. After calling the connectDots method on
the example shown above, the map should appear as follows:
Challenge: sort
The robot is initially facing east on the northwest corner of a
rectangular room (of unknown size) containing piles of dark blocks (of
unknown sizes, in an unknown arrangement).
Write a method called sort to arrange the piles from smallest
to largest, as illustrated in the sample solution below. You
should not need to use any additional Java constructs.
