Write a program in a language with name A that, given a string S, outputs the name of a different programming language B. The length of B must be equal to the Levenshtein distance (abbr. "LD") between A and S. To be considered a programming language, B must have an esolangs page or a Wikipedia page.


(Suppose the program is coded in Python)
Input: Jython
Output: R
Input: Pyt4oq
Output: Go
Input: Rs7hon
Output: C++

The LD between Python and Jython is one, so the output R

You only need to cover up to an LD of up to 12. You can assume that an LD of 0 will never occur.

This is , so the shortest program in bytes wins.

(This is my first challenge! Feedback is appreciated)


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  • \$\begingroup\$ Why 12? Are there not languages with larger names? \$\endgroup\$ Commented Sep 29, 2015 at 2:26
  • \$\begingroup\$ @CᴏɴᴏʀO'Bʀɪᴇɴ It just seemed liek a reasonabl upperbnd. \$\endgroup\$
    – Seadrus
    Commented Sep 29, 2015 at 2:27
  • \$\begingroup\$ @ThomasKwa I believe R is a programming language... it could have easily been C, D, etc. \$\endgroup\$
    – Seadrus
    Commented Sep 29, 2015 at 2:35
  • 1
    \$\begingroup\$ so, you mean a name with a length equal to the Levenshtein distance? What counts as a programming language? Must it have an esolangs/Wikipedia page? \$\endgroup\$
    – lirtosiast
    Commented Sep 29, 2015 at 2:38
  • 7
    \$\begingroup\$ The LD of "Patton" and "Python" is 2, not 3. \$\endgroup\$ Commented Sep 29, 2015 at 11:10

6 Answers 6


PHP, 137 135

Requires error reporting off and PHP 5.4+. Input is GET variable a.



00000000: 3C 3F 3D 65 78 70 6C 6F - 64 65 28 7E DF 2C 7E AD |<?=explode(~ ,~ |
00000010: DF BC DC DF BC D4 D4 DF - B5 9E 89 9E DF AC 9C 9E |                |
00000020: 93 9E DF BE 8A 8B 90 B6 - 8B DF BE 8D 91 90 93 9B |                |
00000030: BC DF AB B6 D2 BD BE AC - B6 BC DF BD 8A 9D 9D 93 |                |
00000040: 9A 98 8A 92 DF B5 9E 89 - 9E 8C 9C 8D 96 8F 8B DF |                |
00000050: B2 9E 8B 97 9A 92 9E 8B - 96 9C 9E DF BE 9C 8B 96 |                |
00000060: 90 91 AC 9C 8D 96 8F 8B - 29 5B 6C 65 76 65 6E 73 |        )[levens|
00000070: 68 74 65 69 6E 28 50 48 - 50 2C 24 5F 47 45 54 5B |htein(PHP,$_GET[|
00000080: 61 5D 29 2D 31 5D 3B    -                         |a])-1];|

Readable version:

<?=explode(' ','R C# C++ Java Scala AutoIt ArnoldC TI-BASIC Bubblegum Javascript Mathematica ActionScript')[levenshtein(PHP,$_GET[a])-1];

C, 183

main(s){char* a[12]={"R","C#","C++","Java","COBOL","Python","Clipper","VBScript","Smalltalk","Javascript","Mathematica","ActionScript"};printf(a[strlen(gets(&s))-!!strchr(&s,67)-1]);}

Picking a language with a one character name lets you cheat with the distance calculation: any string's distance from "C" is just the length of the string, minus one if it includes "C". I imagine R or J could beat this using the same strategy.

  • \$\begingroup\$ How come gets(&s) doesn't crash? \$\endgroup\$
    – anatolyg
    Commented Sep 30, 2015 at 9:13
  • \$\begingroup\$ I'm not sure, it works on Anarchy Golf and ideone but is clearly not really cricket. I imagine it's using the unused memory allocated for ARGV. \$\endgroup\$
    – histocrat
    Commented Sep 30, 2015 at 13:12
  • \$\begingroup\$ I'm a bit late, but a[9];main(s){gets(a);s=strlen(a)-!!strchr(a,67);printf("S%s","\0R\0oT\0taq\0ADOL\0onata\0nowman\0nowball\0nowflake\0tackstack\0hakespeare\0pyrodecimal"+s*~-s/2);} is 162 bytes and avoids the worst of the compiler-specific behavior. It still requires ASCII, two's complement ~, and sizeof(int)>1. \$\endgroup\$
    – benrg
    Commented Jan 15, 2021 at 17:30

Perl 5, 325 276

Using a bit of recursion to calculate the Levenshtein distance.

@X=(P,e,r,l);$y=@Y=split//,pop;sub L{my($n,$m)=@_;return$m,if!$n;return$n,if!$m;my$c=$X[$n]eq$Y[$m]?0:1;(sort{$a<=>$b}(L($m-1,$n)+1,L($m,$n-1)+1,L($m-1,$n-1)+$c))[0]}print qw(C C# C++ Java COBOL Python Clipper VBScript Smalltalk Javascript Mathematica ActionScript)[L(4,$y)-1]

My original version had some issues with the longer inputs.
Till I realised that the Perl sort function sorts alphabetically.

Using substrings instead of arrays turns out to make it slightly longer.

@L=qw(C C# C++ Java COBOL Python Clipper VBScript Smalltalk Javascript Mathematica ActionScript);sub l{my($s,$t)=@_;return length($t)if!$s;return length($s)if!$t;my($u,$v)=(substr($s,1),substr($t,1));substr($s,0,1)eq substr($t,0,1)?l($u,$v):(sort{$a<=>$b}(l($u,$v),l($s,$v),l($u,$t)))[0]+1}print$L[l('Perl',pop)-1]


$ perl levenshtein.pl Php

O, 107 bytes

Using the tip from @histocrat to make the distance calculation simpler. Also used languages with The same starting letter to remove a few characters


Try it here


J, 115 bytes


This is using histocrat's calculation trick (using a 1-letter language), and generates the following list of languages:



   {&((}.&'YABC'&.>|.i.4),(g'SMITHb'),'Clojure';(g'ComeFrom2'),((g=:}:;])'StackStacks'),<'CoffeeScript')@<:@(#-'J'&e.) 'C++'
   {&((}.&'YABC'&.>|.i.4),(g'SMITHb'),'Clojure';(g'ComeFrom2'),((g=:}:;])'StackStacks'),<'CoffeeScript')@<:@(#-'J'&e.) 'ActionScript'
   f 'Jython'
   f 'Python'

05AB1E, 73 bytes

Not even a single-character language name and still the shortest answer here!


Try it online!

•äƵí•hR.L<U...Xè'Sìá  # full program
                   á  # get only letters of...
       .L             # Levenshtein distance between...
                      # implicit input...
       .L             # and...
•äƵí•                 # 14793296...
     h                # in hexadecimal...
      R               # reversed...
         <            # minus 1...
          U   Xè      # th element of...
           ...        # ["", "R", "oT", "taq", "ADOL", "onata", "now man", "now ball", "nowf lake", "tack stack", "hakespeare", "p yro decimal"]
                  ì   # prepended with...
                'S    # literal

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