ioccc/2000/robison

Best game:

Arch D. Robison
1406 Country Lake Drive
Champaign IL 61821
USA

Judges' Comments:

To build:

make robison

To run:

./robison

The program plays almost always reasonably, but does not always detect
illegal moves.  Try "9 1" as your first move, then "13 2". Also it
tends to think for quite a while in the beginning of a game. It is
also smart enough to give up by making a losing move at the end of
a game when its position is hopeless.

Unfortunately, due to the contest rules, we're unable to grant the
author a patent he applied for.  :-)

Selected Author's Comments:

TITLE OF INVENTION

Highly Compressed Program for Playing Hygienic Checkers

FIELD OF INVENTION

The present invention generally relates to checkers.

BACKGROUND OF THE INVENTION

Within the field of checkers, the problem of finding a hygienic opponent
is difficult, as good opponents are peculiar to the tavern habitat of
cracker-barrels, pot-belly stoves, tobacco, and spittoons.

BRIEF SUMMARY OF THE INVENTION

The present invention plays checkers without spitting.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE INVENTION

FIG. 1 shows a numbering of positions.

FIG. 2 shows a numbering of directions.

FIG. 3 shows a sample board.

FIG. 4 shows a method in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Operator plays Black (x); the program plays White (o).  Said Black goes
first.  On operators turn, said program requests a position and direction.
FIG. 1 shows the numbering of the squares.  FIG. 2 shows the numbering of
directions.  As per standard rules, if one or more jumps are possible, one
 of the jumps must be taken in preference to other moves.  Said operator
enters the numbers for the position and direction.  If after jumping over a
piece, another jump is possible, and said piece did not become a king after
said jump, standard rules require that another jump be taken.  In said case,
said program requests a direction only in which to continue jumping from the
present position.  Kings are denoted by upper case.  FIG 3. shows a sample
board.  There is a black king (X) on square 30 and a red king (O) on square
2. The numbers on the right are the numbers of the rightmost square in each
row.

A player loses if they cannot make a legal move.  Said loss is trivially
true if player loses all of his/her pieces.  The present invention announces
said loser.

FIG. 4 shows a C program in accordance with the present invention.  Control
flow is straightforward: control enters routine ``main'', executes a
plurality of statements, and exits via return statement.  FIG. 4 presumes
that type int is 32 bits and short is 16 bits, which are essential to the
preferred embodiment of the invention.  FIG. 4 also presumes that the host
computer uses ASCII encoding for characters. It should be obvious that
practitioners skilled in the art of C programming can remove said
limitations.

The disclosure here describes a particular embodiment of the present
invention, and other embodiments within the spirit of this disclosure
are possible, as well as consumption of spirits while playing.

CLAIMS

I claim, by letters patently absurd:

1.  A method for playing checkers on a computer-based system, where said
    method's source code fits into 1536 countable bytes of source code,
    where a byte is countable if

        (a) it is not whitespace and
        (b) it is not a {, }, or ; immediately followed by whitespace.

2.  The method of claim 1, further comprising a method of alpha-beta pruning
    that exploits the zero-sum nature of the game to unify alpha
    and beta cuts.

3.  The method of claim 1, further comprising the step of formatting the
    source code with short lines, in order to impress manager with
    high productivity, when measured in lines of code.

4.  The method of claim 3, further comprising the step for telling
    skeptical manager that this is the well-known technique of
    "linear programming".

5.  The method of claim 1, where ~- and -~ replace the obvious arithmetic
    operations.

6.  The method of claim 1, further comprising a method where

        (a) strings are encrypted in a manner suitable as C strings, and
        (b) 7-bit ASCII characters with uniform distribution are maximally
            packed subject to the restriction that
        (c) each byte is not countable.

7.  A method for a computer-based system that uses a single shared code
    sequence to either sum a plurality of bits in an N-bit word or reverses
    them, in lg(N) time, depending upon a parameter.

DRAWINGS

FIG 1.

        +--+--+--+--+--+--+--+--+
        |32|  |31|  |30|  |29|  |
        +--+--+--+--+--+--+--+--+
        |  |28|  |27|  |26|  |25|
        +--+--+--+--+--+--+--+--+
        |24|  |23|  |22|  |21|  |
        +--+--+--+--+--+--+--+--+
        |  |20|  |19|  |18|  |17|
        +--+--+--+--+--+--+--+--+
        |16|  |15|  |14|  |13|  |
        +--+--+--+--+--+--+--+--+
        |  |12|  |11|  |10|  | 9|
        +--+--+--+--+--+--+--+--+
        | 8|  | 7|  | 6|  | 5|  |
        +--+--+--+--+--+--+--+--+
        |  | 4|  | 3|  | 2|  | 1|
        +--+--+--+--+--+--+--+--+

FIG. 2.

        1   0
         \ /
          .
         / \
        3   2

FIG. 3.

        o o X .  29
         o . . . 25
        o . . o  21
         . o . o 17
        x . . .  13
         . . x .  9
        x x . .   5
         x x O x  1

FIG. 4

[See attached listing.]