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Rule 110 is a cellular automaton with some interesting properties. Your goal is to simulate a rule 110 in as few characters as possible.

For those who don't know, rule 110 is simulated line by line. Each square in a line looks at the squares above, above-left and above-right to determine what cell it should be.

current pattern  111 110 101 100 011 010 001 000
new cell          0   1   1   0   1   1   1   0

Input: numbers from 0 to 39 representing top row nth input square, separated by commas.

Example input:

38,39

Output: A 40 x 40 grid representing the automata running including the first row. You should leave 0 as blank and 1 as any character.

Example output:

                                  XX
                                 XXX
                                XX X
                               XXXXX
                              XX   X
                             XXX  XX
                            XX X XXX
                           XXXXXXX X
                          XX     XXX
                         XXX    XX X
                        XX X   XXXXX
                       XXXXX  XX   X
                      XX   X XXX  XX
                     XXX  XXXX X XXX

etc.

Note: A similar question about 1D cellular automata has already been asked, but I hope that, by using only one rule, shorter answers can be written.

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4  
Do the patterns wrap around (i.e. does the left-most cell check the right-most cell in the line above it)? –  Ventero Jul 14 at 7:15
2  
If it's singular, then it's a cellular automaton. –  ClickRick Jul 14 at 9:14
    
Do we have to take input as a comma-delimited string or (if we write a function) can we take a list of numbers as input? (At least one answer does the latter.) –  Martin Büttner Jul 14 at 9:55
1  
The answers may be fractionally shorter than Simulate any 1D cellular automaton because the rule is hard-coded rather than having to be parsed from the input, but other than that the answers are going to be the same. If it were a different rule then there would be potential for savings, but how on Earth would special-casing a Turing-powerful rule save anything over a general implementation? –  Peter Taylor Jul 14 at 12:57
1  
@Ventero They do not in this version. –  qwr Jul 14 at 22:17

12 Answers 12

up vote 1 down vote accepted

CJam - 47

S40*l',/{i'!t}/{N40,S3$S++f{>3<2b137Yb='!^}}39*

It uses ! for "1" cells.

Try it at http://cjam.aditsu.net/

Explanation:

S40* makes a string (array) of 40 spaces
l',/ reads a line and splits by comma
{…}/ executes the block for each item (the numbers in string form)
- i'!t converts the number to integer and sets the item at that position in the previous string (initially 40 spaces) to '!'
At this point we have obtained the first line.
{…}39* executes the block 39 times
- N adds a newline
- 40, makes the array [0 1 … 39]
- S3$S++ copies the previous line (position 3 on the stack) and pads it with a space on each side
- f{…} executes the block for {each number from 0 to 39} and {the padded line}
-- >3< takes a slice of 3 items from the padded line starting at the current number
-- 2b converts from base 2; the items we sliced are not base-2 digits, but characters get converted to their ASCII values and ' ' mod 8 is 0 and '!' mod 8 is 1
-- 137Yb converts 137 to base 2 (Y = 2), obtaining [1 0 0 0 1 0 0 1], which is 110 reversed and negated (on 8 bits)
-- ='!^ gets the corresponding base-2 digit (the array wraps around so the index is taken mod 8) and xor's it with the '!' character, resulting in '!' for 0 and ' ' for 1

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Ruby, 113 characters

c=[0]*41
eval"[#{gets}].map{|i|c[i]=1}"+'
c=(0..39).map{|x|putc" X"[u=c[x]]
110[4*c[x-1]+2*u+c[x+1]]}<<0;puts'*40

Takes input on stdin. To use a different rule, simply replace the 110 in the last line with whatever rule you want to try.

Example:

$ ruby 110.rb <<< 38,39
                                      XX
                                     XXX
                                    XX X
                                   XXXXX
                                  XX   X
                                 XXX  XX
                                XX X XXX
                               XXXXXXX X
                              XX     XXX
                             XXX    XX X
                            XX X   XXXXX
                           XXXXX  XX   X
                          XX   X XXX  XX
                         XXX  XXXX X XXX
                        XX X XX  XXXXX X
                       XXXXXXXX XX   XXX
                      XX      XXXX  XX X
                     XXX     XX  X XXXXX
                    XX X    XXX XXXX   X
                   XXXXX   XX XXX  X  XX
                  XX   X  XXXXX X XX XXX
                 XXX  XX XX   XXXXXXXX X
                XX X XXXXXX  XX      XXX
               XXXXXXX    X XXX     XX X
              XX     X   XXXX X    XXXXX
             XXX    XX  XX  XXX   XX   X
            XX X   XXX XXX XX X  XXX  XX
           XXXXX  XX XXX XXXXXX XX X XXX
          XX   X XXXXX XXX    XXXXXXXX X
         XXX  XXXX   XXX X   XX      XXX
        XX X XX  X  XX XXX  XXX     XX X
       XXXXXXXX XX XXXXX X XX X    XXXXX
      XX      XXXXXX   XXXXXXXX   XX   X
     XXX     XX    X  XX      X  XXX  XX
    XX X    XXX   XX XXX     XX XX X XXX
   XXXXX   XX X  XXXXX X    XXXXXXXXXX X
  XX   X  XXXXX XX   XXX   XX        XXX
 XXX  XX XX   XXXX  XX X  XXX       XX X
XX X XXXXXX  XX  X XXXXX XX X      XXXXX
XXXXXX    X XXX XXXX   XXXXXX     XX   X
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Mathematica, 122 bytes

f[a_]:=Riffle[CellularAutomaton[110,Array[If[MemberQ[ToExpression["{"<>a<>"}"],#-1],1,0]&,40],39]/.0->" "/.1->"X","
"]<>""

Yes, you might view this as abusing this loophole, but a) that loophole is quite disputed, b) a Cellular Automaton question needs a Mathematica answer (especially one about Rule 110) and c) Ventero's Ruby answer is shorter anyway, so I don't think any harm is done.

Most of the characters are used for input parsing and output formatting. The actual automaton is simulated using

CellularAutomaton[110,initialGrid,39]

This uses periodic boundary conditions (so the grid wraps around).

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Python - 141

i=input()
o=range(40)
l=''.join(' X'[c in i]for c in o)
for r in o:print l;l=''.join('X '[l[c-1:c+2]in('XXX','   ','X  ','','  ')]for c in o)

Run as e.g. python 110.py <<< 38,39

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2  
['X',' '] could be changed to 'X ' to save 5 characters. –  Calvin's Hobbies Jul 14 at 8:14
    
Thanks @Calvin'sHobbies! Made the change. –  Alex L Jul 14 at 8:18
3  
My favourite fruit is now an o=range() –  kitcar2000 Jul 15 at 17:19

q (67 chars)

Assumes no wrap-around:

{40{not(flip(prev;::;next)@\:x)in 3 cut 111100000b}\@[40#0b;x;not]}
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Python, 186

def r(s,m=range(40)):
 s=[int(i in s)for i in m]
 for g in m:print''.join([' X'[i]for i in s]);s=[int(not''.join(map(str,s[i-1:i+2]if i else s[:2]))in'111 100 000 00'.split())for i in m]

Decent but probably not optimal.

You didn't specify how input is gotten so I just made a function.

Use example:

r([38,39])

Output:

                                      XX
                                     XXX
                                    XX X
                                   XXXXX
                                  XX   X
                                 XXX  XX
                                XX X XXX
                               XXXXXXX X
                              XX     XXX
                             XXX    XX X
                            XX X   XXXXX
                           XXXXX  XX   X
                          XX   X XXX  XX
                         XXX  XXXX X XXX
                        XX X XX  XXXXX X
                       XXXXXXXX XX   XXX
                      XX      XXXX  XX X
                     XXX     XX  X XXXXX
                    XX X    XXX XXXX   X
                   XXXXX   XX XXX  X  XX
                  XX   X  XXXXX X XX XXX
                 XXX  XX XX   XXXXXXXX X
                XX X XXXXXX  XX      XXX
               XXXXXXX    X XXX     XX X
              XX     X   XXXX X    XXXXX
             XXX    XX  XX  XXX   XX   X
            XX X   XXX XXX XX X  XXX  XX
           XXXXX  XX XXX XXXXXX XX X XXX
          XX   X XXXXX XXX    XXXXXXXX X
         XXX  XXXX   XXX X   XX      XXX
        XX X XX  X  XX XXX  XXX     XX X
       XXXXXXXX XX XXXXX X XX X    XXXXX
      XX      XXXXXX   XXXXXXXX   XX   X
     XXX     XX    X  XX      X  XXX  XX
    XX X    XXX   XX XXX     XX XX X XXX
   XXXXX   XX X  XXXXX X    XXXXXXXXXX X
  XX   X  XXXXX XX   XXX   XX        XXX
 XXX  XX XX   XXXX  XX X  XXX       XX X
XX X XXXXXX  XX  X XXXXX XX X      XXXXX
XXXXXX    X XXX XXXX   XXXXXX     XX   X
share|improve this answer
    
I did specify input: in your case you would have to use input() and format the input as specified in the original post. –  qwr Jul 15 at 19:09

Mathematica, 113 chars

Another Mathematica answer using CellularAutomaton.

Print@@" "["X"][[#]]&/@CellularAutomaton[110,SparseArray[#+1->1&/@ImportString[InputString[],"CSV"][[1]],40],39];
share|improve this answer
    
Interesting, how does " "["X"][[#]]& work? –  Martin Büttner Jul 14 at 10:59
    
@m.buettner " "["X"][[1]] is "X". " "["X"][[0]] returns the head of " "["X"], namely " ". –  alephalpha Jul 14 at 11:10
    
Oh, I see. So that's just generally saving a character for lists. That's really clever. I guess you could add it to codegolf.stackexchange.com/questions/12900/… –  Martin Büttner Jul 14 at 11:15

Lua - 351

Not the ideal language for golfing.

s,n,t,u=arg[1],{},table.remove,table.insert
for i=1,40 do u(n,i,'.') end
for i in s:gmatch("%d+")do u(n,i,'x');t(n)end
function a(b) c="";for i=1,40 do c=c..b[i] end;print(c);return c end
for i=1,40 do z= n[40]..a(n)..n[1];for k=2,41 do y=string.sub(z,k-1,k+1);if y=="xxx"or y=="x.." or y=="..." then u(n,k-1,'.')else u(n,k-1,'x')end;t(n)end end
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C - 178

This code depends on the fact that each row in a matrix is stored in contiguous memory. Also, it does not print the first row, but it prints the next 40 ones, since the rules only specified a 40x40 grid.

Indented for readability only, the byte count only includes necessary code.

a[41][42],i,j,*t;
main(){
    while(scanf("%d,",&j)>0)
        a[i][j]=1;
    for(;i<40;i++,puts(""))
        for(j=0;++j<40;)
            t=&a[i][j],
            putchar((*(t+42)=1&(110>>(*(t+1)?1:0)+(*t?2:0)+(*(t-1)?4:0)))?88:32);
}
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Update: Correct output example here (with 40 lines not 50): New output below (removed previous one for brevity):

                                      xx
                                     xxx
                                    xx x
                                   xxxxx
                                  xx   x
                                 xxx  xx
                                xx x xxx
                               xxxxxxx x
                              xx     xxx
                             xxx    xx x
                            xx x   xxxxx
                           xxxxx  xx   x
                          xx   x xxx  xx
                         xxx  xxxx x xxx
                        xx x xx  xxxxx x
                       xxxxxxxx xx   xxx
                      xx      xxxx  xx x
                     xxx     xx  x xxxxx
                    xx x    xxx xxxx   x
                   xxxxx   xx xxx  x  xx
                  xx   x  xxxxx x xx xxx
                 xxx  xx xx   xxxxxxxx x
                xx x xxxxxx  xx      xxx
               xxxxxxx    x xxx     xx x
              xx     x   xxxx x    xxxxx
             xxx    xx  xx  xxx   xx   x
            xx x   xxx xxx xx x  xxx  xx
           xxxxx  xx xxx xxxxxx xx x xxx
          xx   x xxxxx xxx    xxxxxxxx x
         xxx  xxxx   xxx x   xx      xxx
        xx x xx  x  xx xxx  xxx     xx x
       xxxxxxxx xx xxxxx x xx x    xxxxx
      xx      xxxxxx   xxxxxxxx   xx   x
     xxx     xx    x  xx      x  xxx  xx
    xx x    xxx   xx xxx     xx xx x xxx
   xxxxx   xx x  xxxxx x    xxxxxxxxxx x
  xx   x  xxxxx xx   xxx   xx        xxx
 xxx  xx xx   xxxx  xx x  xxx       xx x
xx x xxxxxx  xx  x xxxxx xx x      xxxxx
xxxxxx    x xxx xxxx   xxxxxx     xx   x

Doing another puzzle I learned something interesting about nesting statements in for loops in php, and suddenly they are far more complex than I originally thought. When I get time I reckon I can beat this score considerably. For now though it remains unchanged at a non-competitive 408.


My php version 408 characters:

This was a great puzzle. I also spent ages playing with the inputs as these are fascinating things it must be said. Anyway, here is my PHP version (which is nowhere near as good as some of the answers posted but is complete. In 0th position only take above and above right, in 39th position only take above and above left, ie no wrapping. So here is my version:

<?php $a='38,39';$b='';$d=explode(',',$a);for($i=0;$i<40;++$i){$c=' ';
foreach($d as $k=>$v){if($v == $i){$c='x';}}$b.=$c;}echo $b."\n";
for($x=1;$x<41;++$x){$o='';for($i=1;$i<41;++$i){if(($i>1)AND(substr($b,$i-2,1)=='x')){
$l=1;}else{$l=0;}if((substr($b,$i-1,1))=='x'){$v=1;}else{$v=0;}if((substr($b,$i,1))=='x'){
$r=1;}else{$r=0;}if((($l+$v+$r)==2)OR(($v+$r)==1)){$o.='x';}else{$o.=' ';}}
echo $o."\n";$b=$o;}?>

You can see it and run it here: http://codepad.org/3905T8i8

Input is a input string at the start as $a='38, 39';

Output is as follows:

xx removed as was too long originally - had 50 lines, not 40 xx

Hope you like it!!!

PS I had to add a few line breaks to the code so you could see all of it and not have it stretch accross the page with a scroll bar.

share|improve this answer
    
Your output has 50 lines –  aditsu Jul 15 at 19:20
    
Ah, that was because I was playing with it after I finished and seeing what happened. Altering the rules slightly has such interesting affects. Anyway have changed it to 40 now and sorry for missing that. –  Paul Drewett Jul 16 at 5:36
    
You may want to change the output too :p –  aditsu Jul 16 at 6:35
    
Corrected the output and added new codepad link with correct value. Thank you again. –  Paul Drewett Jul 16 at 12:49

Java, 321 characters

Input passed as argument from command line, for example java R 38,39

I have never written more obfuscated java code :-)

class R{public static void main(String[]a) {
Integer s=40;boolean[]n,o=new boolean[s];
for(String x:a[0].split(","))o[s.valueOf(x)]=s>0;
for(Object b:o){n=o.clone();
for(int j=0;j<s;j++){
boolean l=j>1&&o[j-1],r=o[j],c=j+1<s&&o[j+1];
n[j]=!(l&c&r|l&!c&!r|!(l|c|r));
System.out.print((r?"X":" ")+(j>s-2?"\n":""));
}o=n;}}}
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Golfscript - 12

You should leave 0 as blank and 1 as any character.

Using blank for 1:

;' '40*n+40*
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Har har, very funny :p –  aditsu Jul 15 at 18:49
2  
or not –  Martin Büttner Jul 15 at 18:59

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