Friday, 22 May 2009

BF Joust King of the Hill

BF Joust is a capture the flag programming game based on the esoteric Brainf*** programming language. Recently ais523 revised the language and enviroment, setting up a king of the hill tournament.

The game is played between two programs on a tape with a length randomly chosen between 10 and 30 cells. The cells initially contain 0 with the exception of the cells at either end which contain the flag 128.

Each program views the tape with their own flag on the left and the opponent's flag on the right. The object of the game is to find and set the opponents flag to 0 and keep it 0 for two consecutive cycles. If a program's pointer points to a location off the tape, it loses.

Here's a quick summary of the instruction set:

OpDescription
<move the pointer to the left
>move the pointer to the right
+add 1 to the value stored at pointer
-subtract 1 from the value stored at pointer
[jump past the matching ] if the cell at pointer is 0
]jump to instruction after matching [ unless cell at pointer is 0
.no operation, do nothing

The interpreter also understands certain macros. Instructions inside parentheses are repeated a number of times. For example (>-)*4 expands to >->->->-.

For full details see the rules on the BF Joust Wiki page and check the current hill standings. To submit a program to the BF Joust hill, join the channel #esoteric on irc.freenode.net and send a message to egobot:
/msg egobot !bfjoust program_name program_code
It isn't possible to remove a program, but it can be replaced by submitting another with the same name.

Finally, I'll leave you with the code for shortsword the current king of the hill with 100% wins ;-)
(>++>--)*2(>)*6([-[+]]>)*20
The standings:
ID Score Pts Program
18 90.00 18 shortsword.bfjoust
19 71.12 12 stranger.bfjoust
16 69.75 11 scythe_impomatic.bfjoust
1 59.38 9 ais523_attack5.bfjoust
6 42.50 4 ais523_defend5.bfjoust
2 41.50 6 ais523_attackslow.bfjoust
7 38.00 2 asie1.bfjoust
0 37.00 0 ais523_attack2.bfjoust
12 32.38 -1 fool1.bfjoust
9 28.00 0 attack1.bfjoust
4 18.25 -4 ais523_defend0_1.bfjoust
3 16.25 -5 ais523_defend0.bfjoust
11 11.88 -9 ehirdomatic.bfjoust
10 10.50 -7 defend1.bfjoust
5 10.50 -5 ais523_defend1.bfjoust
17 5.62 -4 shield.bfjoust
15 5.62 -9 programname.bfjoust
14 2.62 -10 nop.bfjoust
8 2.62 -8 asie2.bfjoust
20 0.00 0 stuff.bfjoust
13 0.00 0 iwin.bfjoust
Let me know if you have any success with BF Joust.

5 comments:

  1. BF? this was that whole thing that came out of where perl stands?

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  2. It would be much easier to find this post if you called the language by its name, Brainfuck, rather than "Brainf***". Whose interests are served by censoring the very subject of your post?

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  3. henrah: unfortunately the correct name offends some people, so it's often censored to Brainf***, Brainf**k or Brainf*ck. I guess I can't please everyone! ;-)

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  4. The hill's now been revised to be finite, and it's actually working (it was upside-down for a while...). It's interesting to see a defence program top of the list; this version seems to have more strategies than the old one.

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  5. Hill's working and running smoothly for anyone who's interested.

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