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Code Golf: Sierpinski's Triangle

由 梦想的初衷 提交于 2019-11-28 17:12:57
gnibbler

Golfscript - 46

' /\ /__\ '4/{).+: ;.{ \ ++}%\{.+}%+~ ]}@~(*n*

Golfscript - 47

' /\ /__\ '4/): ;{  +: ;.{ \ ++}%\{.+}%+}@~(*n*

Golfscript - 48

' ': '/\ /__\\'+4/{2 *: ;.{ \ ++}%\{.+}%+}@~(*n*

Golfscript - 51

~' ': '/\ /__\\'+4/\(,{;2 *: ;.{ \ ++}%\{.+}%+}%;n*

Same algorithm as my shorter python ( and ruby ) answer

Golfscript - 78

2\~(?,{-1*}$1: ;{"  ":$*. 2base.{[$$+' /\ ']=}%n+@@{[$$+"/__\\"]=}%n .2*^: ;}%

Same algorithm as my longer python solution

This one has significant newlines

2\~(?,{-1*}$1: ;{"  ":
*. 2base.{[
2*' /\ ']=}%n+@@{[
2*"/__\\"]=}%n .2*^: ;}%

J

46 characters, reading from stdin.

(,.~,~[,.~' '$~#,#)^:(<:".1!:1]3)' /\',:'/__\'

\n always delimits sentences, which made it impossible to fit inside S3 (only 54 characters to play with). S4 is a bit big at 162, so I padded it to fit. Serendipitously, /\ is a legal adverb. ☺

               /\
              i=:3
             /\  /\
            %r=:1!:1
           /\      /\
          t=:]    [r+i
         /\  /\  /\  /\
        b=:' /\',:'/__\'
       /\              /\
      i=:1            -".t
     /\  /\          /\  /\
    h=:(' '$        ~#,#),.]
   /\      /\      /\      /\
  s=:(    h^:1    ,d=:    ,.~)
 /\  /\  /\  /\  /\  /\  /\  /\
(,,&(10{a.)"1[s^:(-i)b)(1!:2)(4)
  • 5
    It's 60 characters. Challenge asks for a full program. – LiraNuna Nov 13 '09 at 3:22
  • 8
    Aww, there's are two sleepy smilies there (~,~) and a smiling one! (=]). This is so cute! – LiraNuna Nov 13 '09 at 7:49
  • I actually see another one :( – RCIX Nov 14 '09 at 0:29
  • 1
    I already gave you +1 on Friday :p, but the triangle is fantastic – John La Rooy Nov 15 '09 at 22:51
  • 1
    Also :'/ and :] – Callum Rogers Aug 7 '10 at 21:30
24
votes

Sorry I'm late. This is based on A. Rex's Perl solution:

                           &I                               
                          ;for                              
                         $x  (2                             
                        ..<>){$E                            
                       .=      $E                           
                      ;my$    y;3*                          
                     33  +3  **  3;                         
                    s".+"$y.=$n.$&x2                        
                   ,$              E.                       
                  $&.$            E"ge                      
                 ;;  $_          .=  $y                     
                }print;;        sub I{($                    
               E,      $n      ,$      F,                   
              $B,$    U)=(    $",$    /,qw                  
             (/   \   _  ))  ;$  _=  $E  .$                 
            F.$B.$E.$n.$F.$U.$U.$B};33333333
  • 3
    That is a thing of beauty!!!! – Drew Hall Nov 13 '09 at 21:42
  • 4
    I was going to do this for golfscript but I didn't have enough characters – John La Rooy Nov 14 '09 at 8:28
16
votes

Go, 273 characters

package main
import(f"fmt";"os";s"strconv";)func main(){var
t=[2]string{" /\\ ","/__\\"};
n,_:=s.Atoi(os.Args[1]);a:=1;N:=a<<uint(n);for
N>0{N-=2;for
k:=0;k<2;k++{for
j:=0;j<N;j++{f.Print(" ")}b:=a;for
b>0{o:=t[k];if
b&1==0{o="    "}f.Print(o);b>>=1}f.Print("\n")}a^=a*2}}

Whitespace is all significant.

Unminized with gofmt sierpinski-3.go | perl -p -e's/\t/ /g':

package main

import (
    "fmt";
    "os";
    "strconv";
)

func main() {
    var t = [2]string{" /\\ ", "/__\\"};
    n, _ := strconv.Atoi(os.Args[1]);
    a := 1;
    N := a << uint(n);
    for N > 0 {
        N -= 2;
        for k := 0; k < 2; k++ {
            for j := 0; j < N; j++ {
                fmt.Print(" ")
            }
            b := a;
            for b > 0 {
                o := t[k];
                if b&1 == 0 {
                    o = "    "
                }
                fmt.Print(o);
                b >>= 1;
            }
            fmt.Print("\n");
        }
        a ^= a * 2;
    }
}

I got a good hint for Go golf here.

  • 5
    I'm guessing that "Go" isn't short for "Golfing Language" – mob Nov 13 '09 at 6:23
  • @mobrule: I only started learning Go yesterday. I'm sure that more experienced Go programmers could do better. Unfortunately there are not many experienced Go programmers since the language was only announced two days ago. See stackoverflow.com/questions/1712172 – user181548 Nov 13 '09 at 8:16
  • 6
    +1 for being early adopter :) – Jonas Gulle Nov 13 '09 at 10:04
  • 1
    The := makes me feel like I'm back in my high school Turbo Pascal class. – gnovice Nov 13 '09 at 14:49
  • 5
    I don't know Turbo Pascal, but in Go x:=1 is short for var x int = 1 and y:="moo" is short for var y string = "moo". It pulls the type off the variable. – user181548 Nov 13 '09 at 16:18
10
votes

Python - 102

a=" /\ ","/__\\"
j=' '
for n in~-input()*j:j+=j;a=[j+x+j for x in a]+[x*2for x in a]
print"\n".join(a)

Python - 105

a=" /\ ","/__\\"
j=' '
for n in(input()-1)*j:j+=j;a=[j+x+j for x in a]+[x+x for x in a]
print"\n".join(a)

Python - 109

a=" /\ ","/__\\"
for n in range(1,input()):j=' '*2**n;a=[j+x+j for x in a]+[x+x for x in a]
print"\n".join(a)

Python2.6 - 120

N=1<<input()
a=1
while N:
 N-=2
 for s in" /\ ","/__\\":print' '*N+bin(a)[2:].replace('0',' '*4).replace('1',s)
 a=a^a*2
9
votes

Perl, 82 strokes

This version no longer prints a trailing newline. Only the first newline is necessary:

$_=' /\ 
/__\\';
for$x(2..<>){
my$y;
$".=$";
s#.+#$y.=$/.$&x2,$".$&.$"#ge;
$_.=$y
}
print

If command-line switches are allowed, then by traditional Perl golf scoring, this is 77+3 strokes (the first newline is literal):

#!perl -p
$\=' /\ 
/__\\';
$y="",
$".=$",
$\=~s#.+#$y.=$/.$&x2,$".$&.$"#ge,
$\.=$y
for 2..$_

Please feel free to edit my answer if you find an improvement.

  • If you're going to make extensive use of switches, you traditionally write it as a shell invocation: perl -pae'code here' (counting all the characters of the shell invocation and the shell quotes as part of the answer, which would also disallow you from using single quotes in your answer). But that might actually get longer. – Chris Lutz Nov 13 '09 at 6:03
  • 1
    @Chris Lutz: Traditional Perl golf scoring is the length of your code plus how many characters you have to add over the usual perl. So in my case, I think it's 77 strokes plus 4 for the extra ` -pa`. – A. Rex Nov 13 '09 at 6:16
  • @ephemient: I wasn't counting the newlines you just deleted anyway; they were there only for readability reasons (if you can say "readability" in this context). After I'm sure you're done editing, I'll change the answer to make that clear. Thanks for the help, though. – A. Rex Nov 13 '09 at 6:18
  • @A. Rex - I've always counted the invocation. (And #!perl isn't a valid shebang line on my system.) – Chris Lutz Nov 13 '09 at 6:26
  • 1
    And (almost) everything you need to know in J is linked from one webpage jsoftware.com/help/dictionary/vocabul.htm – ephemient Nov 13 '09 at 16:46
8
votes

Haskell, 153 149 137 125 118 112 characters:

Using tail recursion:

(%)=zipWith(++)
p="  ":p
g t _ 1=t
g t s(n+1)=g(s%t%s++t%t)(s%s)n
main=interact$unlines.g[" /\\ ","/__\\"]p.read

earlier version, @118 characters:

(%)=zipWith(++)
f 1=[" /\\ ","/__\\"]
f(n+1)=s%t%s++t%t where t=f n;s=replicate(2^n)' ':s
main=interact$unlines.f.read

Using the (justly deprecated!) n+k pattern saved 4 characters.

I like how it comes out halfway readable even in compressed form.

edit:old main

main=do{n<-getLine;putStr$unlines$f$read n}
  • something i just found in the prelude that might help main=readLn>>=putStr.unlines.f – barkmadley Nov 13 '09 at 4:18
  • zipWith! i knew there was a better way to do that – barkmadley Nov 13 '09 at 5:08
7
votes

Perl

94 characters when newlines are removed.

$c=2**<>;$\=$/;for$a(0..--$c){print$"x($c-$a&~1),
map$_*2&~$a?$"x4:$a&1?'/__\\':' /\ ',0..$a/2}
  • You can save 5 characters by reading from stdin with <> if you want. If you don't, pop still saves characters. Either way, you can use the ridiculous construct $c=2**~-<>; or $c=2**~-pop; to save on parentheses around the /2. – A. Rex Nov 13 '09 at 7:51
  • I should have noted -- feel free to edit my answer too :) – ephemient Nov 13 '09 at 14:21
7
votes

Ruby — 85

a=' /\ ','/__\\'
j=' '
2.upto(gets.to_i){j+=j;a=a.map{|x|j+x+j}+a.map{|x|x+x}}
puts a

101 chars — /\-modified solution from Rosetta Code 
(a=2**gets.to_i).times{|y|puts" "*(a-y-1)+(0..y).map{|x|~y&x>0?'  ':y%2>0?x%2>0?'_\\':'/_':'/\\'}*''}
    4
    votes

    Python, 135 chars

    S=lambda n:[" /\\ ","/__\\"]if n==1 else[" "*(1<<n-1)+x+" "*(1<<n-1)for x in S(n-1)]+[x+x for x in S(n-1)]
for s in S(input()):print s
    • 1
      This can be shortened slightly by changing int(raw_input()) to input() – Jeffrey Aylesworth Nov 13 '09 at 2:49
    • Good call. Fixed. – fserb Nov 13 '09 at 2:54
    4
    votes

    MATLAB - 64 characters (script version)

    This assumes that you have the variable N already defined in your workspace:

    A=[' /\ ';'/__\'];for i=1:N-1,B=32*ones(2^i);A=[B A B;A A];end;A

    MATLAB - 78 characters (m-file function version)

    Pass N as an argument to the function s:

    function A=s(N),A=[' /\ ';'/__\'];for i=1:N-1,B=32*ones(2^i);A=[B A B;A A];end
      4
      votes

      C

      Same algorithm as the Perl answer, but weighing in heavier, at 131 necessary characters.

      a,b;main(c,v)char**v;{c=1<<atoi(v[1]);for(a=0;a<c;a++,puts(""))
for(b=c;b--;write(1,b&~a?"    ":a&1?"/__\\":" /\\ ",4-2*(b>a)))--b;}

      I thought write(1,…) was UNIX API, but this seems to compile and run fine on Windows too.

      If you replace char by int, it saves one character and still works, but it's of questionable legality.

      • +1 again for splitting them! – Chris Lutz Nov 13 '09 at 5:51
      • 2
        write() is a Unix API, and part of POSIX, but Windows provides a lot of POSIX functions. They're all "deprecated" so to be "correct" on Windows you should use _write() but a) this is code golf, and b) the idea that POSIX is deprecated makes me giggle. – Chris Lutz Nov 14 '09 at 0:50
      4
      votes

      Logo (not exactly following the requirements): 47 characters

      to F:n if:n[repeat 3[F(:n-1)fd 2^:n rt 120]]end

      I tested this only with http://www.calormen.com/Logo/ so I don't know if it's portable. It doesn't follow the requirements, but surely logo must be the appropriate language here? :) I love that at the time of writing logo is one character short of equalling golfscript and J.

      2
      votes

      Lua, 139 characters

      t={" /\\ ","/__\\"}for i=2,(...)do for j=1,#t do
t[#t+1]=t[j]:rep(2)k=(" "):rep(#t[j]/2)t[j]=k..t[j]..k end end
print(table.concat(t,"\n"))
        2
        votes

        Nroff, 542

        $ nroff -rn=5 file.n

        .pl 1
.nf
.de b
. nr i 0
. while d\\$1\\ni \{\
.   \\$3 \\$1\\ni \\$2\\ni
.   nr i +1
. \}
..
.de push
. nr i 0
. while d\\$2\\ni \{\
.   nr i +1
. \}
. nr j 0
. while d\\$1\\nj \{\
.   ds \\$2\\ni \&\\*[\\$1\\nj]
.   nr i +1
.   nr j +1
. \}
..
.ds l0 \& /\[rs] \&
.ds l1 "/__\[rs]
.ds s \&\ 
.de o
. ds \\$2 \&\\*s\\*[\\$1]\\*s
..
.de p
. ds \\$2 \&\\*[\\$1]\\*[\\$1]
..
.de assign
. ds \\$2 \&\\*[\\$1]
..
.nr a 2
.while \na<=\nn \{\
. ds s \&\*s\*s
. b l m o
. b l n p
. b m l assign
. push n l
. nr a +1
.\}
.de t
\\*[\\$1]
..
.b l zz t
        • Nice. I wonder if TeX would be any better at this? – ephemient Nov 15 '09 at 15:43
        1
        vote

        F#, 225 chars

        let rec p n=if n=1 then" "else p(n-1)+p(n-1)
and S n=if n=1 then[" /\\ ";"/__\\"]else let s=S(n-1)in List.append(List.map(fun s->p(n)+s+p(n))s)(List.map(fun x->x+x)s)
for s in S(int(System.Console.ReadLine()))do printfn"%s"s
        • 4
          There must be a way to shorten this awful System.Console.ReadLine... what a waste of bytes ;) – Thomas Levesque Nov 13 '09 at 3:03
        1
        vote

        Clojure: 174 characters

        Algorithm stolen from others above.

        (doseq[q((fn f[n](if(= n 1)[" /\\ ""/__\\"](let[z(f(dec n))](concat(map #(let[y(repeat(Math/pow 2(dec n))\ )](apply str(concat y % y)))z)(map str z z)))))(read))](println q))

        38 of those characters are parentheses. : (

        (doseq [q ((fn f [n]
           (if (= n 1)
             [" /\\ " "/__\\"]
             (let [z (f (dec n))]
               (concat
                (map #(let [y (repeat (Math/pow 2 (dec n))\ )]
                        (apply str (concat y % y))) z)
                (map str z z))))) (read))] 
  (println q))
          1
          vote

          Python, 120 characters (recursive solution)

          S=lambda n:n<2and[" /\ ","/__\\"]or[" "*n+x+" "*n for x in S(n/2)]+[x+x for x in S(n/2)]
print"\n".join(S(1<<input()-1))

          I started putting on the green where @fserb left off...

            1
            vote

            GolfScript (45 44 chars)

            ~(' /\ /__\ '4/)@{.+\.{[2$.]*}%\{.+}%+\}*;n*

            Similar to gnibbler's solution. My initial attempt was already quite similar, and then I looked at his and borrowed some ideas.

              0
              votes

              Python, 186 chars (UNIX line termination)

              for j in range(1,n):
 for s in p:
  print s
 x=2**j;y=2*x;p.extend(['']*x)
 for i in range(y-1,-1,-1):
  if i<x:
   s=' '*x;p[i]=s+p[i]+s
  else:
   q=p[i-x];p[i]=q+q
              • 4
                Error: name p not defined? – Chris Lutz Nov 13 '09 at 5:58
              0
              votes

              Prolog, 811 Chars

              :- module(sierpinsky, [draw/1]).

% draw(+Level)
draw(N) :- K is 2^(N+1)-1,
  for(Line, 0, K),
  draw2(N, Line, true, nl),
  fail.
draw(_).

% draw2(+Level, +Line, +Before, +After)
draw2(0, 0, Before, After) :- !,
  Before, write(' /\\ '), After.
draw2(0, 1, Before, After) :- !,
  Before, write('/__\\'), After.
draw2(N, Line, Before, After) :- N>0, K is 2^N, Line < K, !, M is N-1,
  draw2(M, Line, (Before, tab(K)), (tab(K), After)).
draw2(N, Line, Before, After) :- N>0, K is 2^N, Line >= K, !, M is N-1,
  Line2 is Line - K,
  draw2(M, Line2, Before, draw2(M, Line2, true, After)).

% for(+Variable, +Integer, +Integer)
for(V, N, M) :- N =< M, V = N.
for(V, N, M) :- N < M, K is N+1, for(V, K, M).

% tab(+Integer)
tab(N) :- for(_, 1, N), write(' '), fail.
tab(_).

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