ioccc/2000/robison

To build:

    make

To use:

    ./robison

Judges' remarks:

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. :-)

Author's remarks:

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 operator's 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 a 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

   • it is not whitespace and
   • 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 the manager with high productivity, when measured in lines of code.

4. The method of claim 3, further comprising the step for telling the 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 * strings are encrypted in a manner suitable as C strings, and * 7-bit ASCII characters with uniform distribution are maximally packed subject to the restriction that 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.]