CMPS203 Programming Assignment 1

Objective

The objective of this assignment is to become familiar with a problem that you will implement in several different programming languages/paradigms this quarter.

A Bit of Background

For this assignment you are to write a program in C, C++, C#, Java, or Python (your choice). The program will compute and print the number of liberties for stones on a Go board, and identify which stones are connected into groups.

Go is played on a square grid with 9, 13, or 19 vertical and horizontal lines. There are two players and they take turns placing black or white stones (one color for each player) on the intersections of the lines.

A “liberty” is an unoccupied intersection, adjacent to a stone. Adjacent means connected by a line (diagonals are not adjacent). For example, a single stone placed away from any edge has four liberties (one north, one south, one east, and one west).

A group of stones of the same color is connected if you can move from any stone in the group to any other stone passing only through intersections occupied by stones of the same color. For example, the following board has three groups (two black groups and one white group).

......W..

..BB..W..

...BWWW..

....B....

.........

Liberties are shared by stones in a group. For example, the upper left black group in the previous example has 6 liberties marked with L in the following:

..LL..W..

.LBBL.W..

..LBWWW..

...LB....

....B....

.........

The white group has 8 liberties.

That is all you need to know about Go for this assignment. You can learn more at any of the many Go sites on the web. This looks like a reasonable place to start: http://www.well.com/user/mmcadams/gointro.html .

Requirements

Your program must adhere precisely to the input and output specifications stated here.

Input: Your program should read its input from standard input. The first line of input will be a single integer, either 9, 13, or 19, specifying the size of the board. If S is the size of the board, then the next S lines will each contain a sequence of S characters from the set {., B, W}. That’s a dot for empty, a B for a black stone, or a W for a white stone.

Output:

If the initial line does not contain one of the integers 9, 13, or 19, your program should print “That is not a legal board size.” and exit.
If any of the subsequent S lines contains a character other than the three specified your program should print “There was an illegal character on line X of the board.” and exit. X is the first line containing an illegal character and the “first” line of the board is “line 1” (although it is the second line of the input). (NOTE: Next time add error messages for short line and too few lines.)
If the input is properly formed, your program should print the board three times. First print the board showing the stones (essentially echoing the input) in the format given below. Then print the board showing the liberties for each group (repeated for each stone in the group) in the format given below, Finally print the board identifying each group of stones in the format given below.
Precede the first printing of the board with a line containing “The Stones”. The first printing of the board will be the same as the input without the initial size and with row and column labels. The columns should be labeled above with consecutive letters starting with “A”. The rows should be labeled on the left with consecutive integers starting with 1. The row label should be followed by a single space character and the integer should use two spaces right justified. That is, single digit integers should be preceded by a single space.
Precede the second printing of the board with a blank line and then the line “The Liberties”. The second printing of the board will contain the same row labels. Each column will be labeled with a repeated letter (e.g. AA, BB, CC). Each column will be 4 characters wide. For each intersection of the board print a space, followed by a 2 digit number of liberties for the group containing the stone at that location, followed by another space. If there are more than 99 liberties, just print 99. For 0-9 liberties print a space followed by the single digit. If the intersection does not contain a stone print two dots/periods.
Precede the third printing of the board with a blank line and then the line “The Groups”. The third printing is like the second but this time print the group number modulo 100 for each occupied intersection and two dots/periods for unoccupied intersections. The groups should be numbered starting with 1. The groups should be ordered such that a left to right, top to bottom scan of the board will make its first encounter with a group in increasing order. If group number modulo 100 results in 0, print a space followed by the single digit 0 (same as for 0 liberties).
The output for the example given earlier should be:

The Stones

ABCDEFGHI

1 ......W..

2 ..BB..W..

3 ...BWWW..

4 ....B....

5 ....B....

6 .........

7 .........

8 .........

9 .........

The Liberties

AA BB CC DD EE FF GG HH II

1 .. .. .. .. .. .. 8 .. ..

2 .. .. 6 6 .. .. 8 .. ..

3 .. .. .. 6 8 8 8 .. ..

4 .. .. .. .. 5 .. .. .. ..

5 .. .. .. .. 5 .. .. .. ..

6 .. .. .. .. .. .. .. .. ..

7 .. .. .. .. .. .. .. .. ..

8 .. .. .. .. .. .. .. .. ..

9 .. .. .. .. .. .. .. .. ..

The Groups

AA BB CC DD EE FF GG HH II

1 .. .. .. .. .. .. 1 .. ..

2 .. .. 2 2 .. .. 1 .. ..

3 .. .. .. 2 1 1 1 .. ..

4 .. .. .. .. 3 .. .. .. ..

5 .. .. .. .. 3 .. .. .. ..

6 .. .. .. .. .. .. .. .. ..

7 .. .. .. .. .. .. .. .. ..

8 .. .. .. .. .. .. .. .. ..

9 .. .. .. .. .. .. .. .. ..