That's a lot of monkeys

The infinite monkey theorem states that, given infinite time, a machine sending an endless stream of random characters will always type any given text.

That sounds to me like a great idea for a challenge.

Process

In order to monkey-ize a string A, the following steps should be taken:

1. Take an empty string. We will call this string B.
2. Pick a uniformly random printable ASCII character (characters in the range 0x20 to 0x7E) and add that character to B.
3. If A is a substring of B, B is our monkey-ized string. Otherwise, repeat step 2 until A is a substring of B.

This process is only an example, easier methods may exist depending on your language. You do not need to follow this method exactly, as long as the same distribution of outputs is achieved.

The challenge

Write a program or function that, given a non-empty string in any reasonable format, returns a monkey-ized version of that string.

Your program only has to practically work for inputs of length 3 or less. For longer inputs, it is allowed to terminate early with or without outputting anything.

Example

Unfortunately, it's kind of hard to create examples for this question due to the random nature of it and the large outputs.

However, I can supply a single example for the input hi, on Hastebin.

Scoring

Since this is , the submission with the fewest bytes wins.

• Sandbox Nov 5, 2017 at 22:38
• Do we need to follow the described procedure to produce the output? If yes, that's an unobservable requirement, which is problematic. If not, we can generate B directly by prepending a non-negative number n of random characters to A. The only real problem then is to know the distribution of n (I bet on a geometric distribution) Nov 5, 2017 at 23:24
• @seshoumara You may not. Nov 6, 2017 at 8:03
• @LuisMendo I thought along these lines, and it's actually not easy to generate the prefix directly. It can't contain the target string, including crossing the boundary where it meets the appended string. And the distribution of prefix lengths depends not just on the length of the target string, but its structure as well.
– xnor
Nov 6, 2017 at 9:03
• Some of the solution computer programs below, such as .W!}zH+ZOrd\k, look a lot like what a monkey has typed. Nov 7, 2017 at 22:46

C, 192 bytes

i;g(s,b,i,n,j)char*s,*b;{for(b[i+1]=0;b[n+j];++n)s[n]-b[n+j]&&(n=-1,++j);return n;}f(char*s){char*b=calloc(strlen(s),1);for(i=0;s[i];)i=(b[i]=putchar(rand()%95+32))-s[i]?i?g(s,b,i,0,0):0:i+1;}


Try it online!

It's a mess now, but at least it works even for the corner cases...

C,  63   62  61 bytes

Thanks to @Jonathan Frech for saving a byte!

i;f(char*s){for(i=0;s[i=putchar(rand()%95+32)-s[i]?0:i+1];);}


Try it online!

• I have absolutely no idea why this halts when it hits s, +1 Nov 5, 2017 at 22:48
• @ATaco It halts when i grows large enough that s[i] refers to the null terminator of the string (character 0). Nov 5, 2017 at 22:52
• Oh, so instead of throwing random characters at it until s is accidentally created, it throws random characters at it until it reaches s. Smart. Nov 5, 2017 at 22:53
• As much as I like this answer, I believe it breaks for an input such as "ab" when the rand monkeys type "aab". Nov 6, 2017 at 14:28
• I guess you need something like KMP so that this approach can be valid. Assume the input string is ababc and the monkey generate !!abababc will your program halt? Nov 6, 2017 at 14:56

Python, 79 bytes

f=lambda x,s='':x in s and s or f(x,s+chr(randint(32,126)))
from random import*


Try it online!

This is theoretically sound, but will crash early due to python's recursion limits (you can set them further to get longer results)

Python, 84 bytes

from random import*
x,s=input(),''
while x not in s:s+=chr(randint(32,126))
print(s)


Try it online!

This one is ought to work for relatively longer strings, since it doesn't rely on recursion, at the cost of 5 bytes.

• You can save three bytes by using backticks to do the string conversion (shown here as single quotes to the the markdown right) s+'randint(32,126)' Nov 6, 2017 at 16:24
• @wnnmaw backticked randint(32,126) would produce a string of the number, not the ascii char mapping Nov 6, 2017 at 16:59

Ohm v2, 10 bytes

Ý£D³ε‽α@§↔


Try it online!

Explanation:

Ý£D³ε‽α@§↔  Main wire, arguments: a (string)

Ý           Push empty string to top of stack
£          Start infinite loop
D³ε‽        If a is a substring of the ToS, break out of the loop
α@§     If not, select a random printable ASCII character...
↔    ...and concatenate it with the ToS


Funky, 64 bytes

s=>{S=""whileS::sub((#S)-#s)!=s S+=S.char(math.random(32,126))S}


This uses a few tricks I've been wanting to use in Funky, like a variable name after a keyword as in whileS, and using the fact that strings implicitly parent to the string library.

Ungolfed

function monkey(target){
monkeyCode = ""
while (monkeyCode::sub((#monkeyCode)-#target)!=target){
monkeyCode += string.char(math.random(32,126))
}
monkeyCode
}


Try it online!

• So would that be... Funky monkeys? Nov 6, 2017 at 9:51

import System.Random
s#(a:b)|and$zipWith(==)s$a:b=s|1>0=a:s#b
m a=(a#).randomRs(' ','~')<$>newStdGen  Try it online! Basic idea is to generate an infinite list of characters with randomRs and stop it once we find the string. C# (.NET Core), 86 bytes a=>{var b="";for(var r=new Random();!b.Contains(a);b+=(char)r.Next(32,127));return b;}  I don't really like how much creating the Random instance takes, but I don't think there's a way around it. Try it online! • Welcome to PPCG! Currently your solution does not properly generate a random character since according the the docs, the upper bound passed to Random.Next(Int32,Int32) is exclusive and so not one of the numbers generated. This can be fixed by replacing 126 by 127. Nov 8, 2017 at 14:45 • @0 ' Whoops, I thought about it while writing, but I forgot to check it before posting. Thanks! Nov 8, 2017 at 14:56 • There is actually a way around that long Random, you can remove the variable declaration! 79 bytes Nov 9, 2017 at 7:48 • @FlipTack Interesting, I tried that in C# Interactive and it didn't work because it just kept generating the same number. Weird to see that it does work in TIO. Nov 9, 2017 at 9:08 GNU sed + coreutils, 75 + 1(r flag) = 76 bytes h : s:.*:shuf -i32-126|dc -e?P:e H;g s:\n::2g /^(.+)\n(.*)\1/{s::\2\1:;q} b  Try it online! (It takes a lot of runs to get an answer for a length 2 input, because most of the time you run out of allowed TIO computation time.) Explanation: h # copy input string 'A' to hold space : # start loop s:.*:shuf -i32-126|dc -e?P:e # run shell script: shuf outputs a rnd permutation #of the set of numbers from 32 to 126, and '?P' in #dc converts the 1st read decimal to an ASCII char H;g # append char to hold space ('A\n.'), then copy #result back to pattern space s:\n::2g # remove all '\n's from pattern space, but first /^(.+)\n(.*)\1/{ # if pattern is 'A\n.*A' (A substring of B), then s::\2\1:;q # search previous regex used and leave only '.*A', #then quit (implicit printing before exit) } b # repeat loop  Benchmark: approximate, for scaling purposes only • input length: 1, 10 random inputs (runs), average time: < 1 s • input length: 2, 10 random inputs (runs), average time: 90 s • input length: 3, 10 random inputs (runs), average time: lots of hours! Perl 5, 31 +2 (-pa) bytes }{$_.=chr 32+rand 95until/\Q@F/


Try it online

• You can save 3 bytes since the \E$ is extraneous – Zaid Nov 7, 2017 at 19:18 • indeed, thank you for having noticed Nov 8, 2017 at 8:09 • saved 2 more bytes Nov 8, 2017 at 8:32 • That's sneaky. Very nice indeed :) – Zaid Nov 8, 2017 at 8:56 • and even more, -3bytes Nov 8, 2017 at 9:32 Japt, 26 bytes @(PbU >-1}a@P+=(Mq95 +32 d  Try it online! • Very quick golf while on a smoke break: 22 bytes. Welcome to Japt :) Nov 25, 2017 at 23:57 R, 7976 75 bytes -3 bytes thanks to MickyT for changing the random sampler -1 byte thanks to Robin Ryder for tweaking the random sampler again function(S){G="" while(!grepl(S,G))G=paste0(G,intToUtf8(32+95*runif(1))) G}  Try it online! • hi, your sample could be replaced with intToUtf8(runif(1,32,127)) Nov 6, 2017 at 21:05 • @MickyT excellent, thank you! Nov 7, 2017 at 15:00 • You can save 1 byte with 32+95*runif(1) as your random sampler. Apr 15, 2019 at 21:41 Charcoal, 1514 12 bytes Ｗ¬№ωθ≔⁺ω‽γωω  Try it online! Link is to verbose version of code. Edit: Saved 2 bytes due to a subsequent bug fix in Charcoal. Explanation:  θ Input string ω Predefined variable w № Count number of occurrences ¬ Logical not Ｗ Loop while true ω Predefined variable w ⁺ Concatenated with γ Predefined printable characters ‽ Random element ≔ ω Assign to predefined variable w ω Predefined variable w Implicitly print  Ruby, 42 bytes ->w,s=""{s+=[*" "..?~].sample;s[w]?s:redo}  Try it online! Pyth - 14 bytes .W!}zH+ZOrd\k  • W!}Qk=+kpOrd\  is 14 bytes as well, SE is messing with formatting because of unprintable but range is generated the same way – Dave Nov 5, 2017 at 23:45 Mathematica, 65 bytes ""//.x_/;x~StringFreeQ~#:>x<>RandomChoice@CharacterRange[32,126]&  Try it online! -3 bytes from Jonathan Frech • I think FromCharacterCode[RandomInteger@94+32] is equivalent to the shorter RandomChoice@CharacterRange[32,126]. Nov 5, 2017 at 23:12 • @JonathanFrech yes,it is! Nov 5, 2017 at 23:18 Lua, 99 102 bytes • Saved a bug thanks to ATaco, which added three bytes. function f(B)s=string S=""while not(s.find(S,B,1,1))do S=S..s.char(math.random(32,126))end print(S)end  Try it online! MATL, 17 16 bytes ''6Y2TZrhtGXfn~  Try it online! -1 byte thanks to Giuseppe Octave, 62 bytes t=input(o="");while(~nnz(regexp(o,t)))o=[o,randi(95)+31];end;o  Try it online! Explanation: t=input(o=""); % get stdin and define output while(~nnz(regexp(o,t))) % while no matches o=[o,randi(95)+31]; % concatenate string with ascii char end; o % output result  Many thanks to Luis Mendo for the edits! • Welcome to the site! :) Nov 6, 2017 at 21:00 • Can't you replace isvector by nnz? And strfind by regexp. Also, you can use randi(95)+31, or maybe replace the whole sprintf statement by o=[o,randi(95)+31]; (implicit conversion to char) Nov 6, 2017 at 23:38 • Also, we usually require a function or a program that takes its input (as opposed to defining a variable containing the input) -- something like this Nov 6, 2017 at 23:48 • I️ attempted to do that, but I️ couldn’t think of a concise way so I️ skipped it. Nice revisions! – Alan Nov 7, 2017 at 0:21 • Feel free to incorporate those suggestions into your answer. That's standard on this site Nov 7, 2017 at 11:37 Japt, 1614 11 bytes ;_øU}a@P±Eö  Try it ;_øU}a@P±Eö :Implicit input of string U _ :Function taking a string as argument øU : Contains U } :End function a@ :Get the first result of the following function that returns true P± : Append to P (initially the empty string) ; E : ASCII ö : Random character  Alice, 21 bytes /U!?"$~dr@
\idwz K"o/


Try it online!

Explanation

/...@
\.../


This is framework for mostly linear programs that operate entirely in Ordinal (string-processing) mode. The IP bounces diagonally up and down through the program twice, which means that the actual code is a bit weirdly interleaved. The commands in the order they're actually executed are:

i!w" ~"rUd?z$Kdo  Let's go through this: i Read all input. ! Store the input on the tape for later. w Push the current IP address onto the return address stack. This marks the beginning of the main loop. " ~" Push this string. r Range expansion. Turns the string into " !...}~", i.e. a string with all printable ASCII characters. U Random choice. Picks a uniformly random character from this string. This will remain on the stack throughout the rest of the program and will form part of the resulting string. d Join stack. This takes all strings on the stack and joins them into a single string and pushes that (it does this without actually removing any elements from the stack). ? Retrieve the input from the tape. z Drop. If the joined string contains the input, everything up to and including the input will be discarded. Otherwise, nothing happens to the joined string. This means that the result will be an empty string iff the joined string ends with the input.$K      If the top of the stack is not empty, jump back to the w to continue
with another iteration of the main loop.
d       Join the stack into a single string once more.
o       Print it.


{("",*~(" ".."~").pick...*~~/$_/)[*-1]}  Try it online! (...)[*-1] returns the last element of the sequence defined by ..., of which: • "" is the first element; • * ~ (" " .. "~").pick generates the next element by appending a random character in the appropriate range to the previous element; and • * ~~ /$_/ is the ending condition, which is that the current element matches the main function's input argument $_ as a literal substring. Java 8, 8179 78 bytes a->{String b="";for(;!b.contains(a);b+=(char)(32+Math.random()*95));return b;}  -1 byte thanks to @OlivierGrégoire for pointing me to a (big >.<) mistake I've made.. Explanation: Try it here. a->{ // Method with String as both parameter and return-type String b=""; // Result-String, starting empty for(;!b.contains(a); // Loop as long as the result does not contain the input b+=(char)(32+Math.random()*95) // Append a random character to b ); // End of loop return b; // Return the result-String } // End of method  • It should be 32+Math.random()*95. There... bug fixed and a byte saved! ;-) Nov 7, 2017 at 18:00 • @OlivierGrégoire Woops.. Looked at the hexadecimal code for the space, but regular decimal for tilde.. >.> Thanks for noticing. Not sure how I've missed that, since the output clearly had 'unprintable' symbols.. Nov 7, 2017 at 18:20 05AB1E, 10 9 bytes (-1 @ Emigna) [žQΩJD¹å#  Try it online! Do the monkey with me. [ | Loop forever. žQ | Push 0x20-0x7E as a single string. .R | Pick from it randomly. J | Join stack (B) with new char. D | Duplicate (B). ¹å | Push input (A) and check if input (A) is in (B). # | If the previous statement is true, break loop.  • You can do Ω instead of .R. Jan 16, 2018 at 13:20 • Lol, using an Ohm, to beat Ohm v2. How nice. Jan 17, 2018 at 14:27 QBIC, 33 bytes ≈instr(Z,;)<1|Z=Z+chr$(_r32,126|)


Explanation

≈instr( , )<1|   WHILE InStr() can't find
;        the input (cmd line string argument) as part of
Z          the output (Z$, which is printed automatically on exit) Z=Z+ add to the output chr$(         )  an ASCII character
_r32,126|   with a random codepoint between 32 and 126 (incl)


Sample run:

Command line: hi

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OH[N/9j1r%vUcox\68{yFemlmmtp*q5kfrlIo3yQB??6jW:TW+)':K#]^=ilF_/N!)=}y@k.y//nhChX!3b=t,1_KhR,n]/_.-P>B80W#'E%J[g?ti)*;Yl]}r0>qh/X[{=)Gr '[+pz|DI=mA8zj~yAT*^7w%tV0l=V^/#2W>)f)X%f^L&+Un}VlQt3.%gEKbE!7adTb#}i!F$-Gug]@*G,hKe;/p,Mb@wBJ4<V&jJd&_H4VR{Hc"{2<l<QapiLw(JK-2-[1_.WR.@CG$?\1<&( QX5c9 :z^jDW09(=iH V/vkcJ8D<uLAr$dbc$Hl'2KTUlbrd8kD{B0Eeu<&oL2s.S4@Jo$zVq~BqeLsb;k-NG/'iU|)W_:X-.XUc<v\elx57ZZ"R!y_yzve*Wlt>.fE,#Eh:(#gn1kSQ+/3NYjD']I;"+@pnW[1EA.AyqM4,0,dJt.?r2oab.j\k@)BsZ|s39FdL87xyuJ0nXX=yz^~W,}acDZp8ukCpv^<^{CkRS<=GsS$}#fbP5%A$GHdg)+WZLLN9[ue073Q!F"J;X^49*$R'W%C.r~Fj&B)tq[01a4En%H,kvyZG|,)%$44rJg[tq<wG9FjN<m@larki#;Bns%D}v_efPRH(OeRq0{=>Uc[~xcTcV_9|k54Q2*N.3]LlmFasY3"p =onbg$M+ReRsnH|9gV~#2?c1-V$35."DZH-O$~,c.gs]%,]p4\OFIW%l:,E,YT8FCeU8hy#lNq1lCpS 0I&q_*q>|=,(-dHuzi~6$GW22*A\w*&R< W$HPRr,2A}3w\"Y?d%{2^xP:GqI\26A|.e'H2Z[M4=P.H87O~{)9|B*tHAC\j^S,StW!*snsz82R!:eD@uB4x+x&zSIN(3V|.^N_$=i=p}iK4h'v"$:I<t e:Y/XrSOF83=lkVNa0^k@jB@{ARE@r=Bja(Bw>@?+Wo,= u5HhXPeRMXS4@H#$-Jwg2"2-]%7p.o2Ar9J6Y1Ra?"3<oee&bpO^O{nw9=%\0brVNXrelWGoJyb/5W%MB0UBaPsc*29K<N~NriWM$"eY0@xh^<$b:E/J~S%{#ry~6d?4Vv@^&9'=iBA#2U]bj9>UoJ#wQDN~6cB&/_Pu-XF?_hu3><(M7RW\%Ly@rTC9^b?kVL~w%[{!&{#aS7<mc@J>ZaN7s}Y.c0:Y.\d&_[L{m|>|>%J^@!i9y0_lwejChi


PHP, 55+1 bytes

while(!strpos(_.$argn,_.$s.=chr(rand(32,126))));echo$s;  Run as pipe with -nR. Not suitable for TIO cause of probable timeout. Insert a space between the quotation marks for PHP older than 7.1. This 51+1 bytes version will fail if input is 0: while(!strstr($argn,$s.=chr(rand(32,126))));echo$s;


Javascript 74 bytes

s=(a,b='')=>~b.search(a)?b:s(a,b+String.fromCharCode(32+Math.random()*95))


call like this:

s('hi')

• @Giuseppe thx, I have it added in the byte count Nov 8, 2017 at 14:37
• I think you have to change 94 to 95 for the code to be valid Nov 9, 2017 at 0:21
• @Hawkings Yea, you're right, fromCharCode ignores decimals it seems. Thanks for pointing it out! Nov 9, 2017 at 9:39
• Save a byte with ~b.search instead of b.includes. Jan 16, 2018 at 11:02
• @Shaggy Nice! Didn't know about search Jan 16, 2018 at 13:07

Julia 0.6, 53 bytes

a->(s="";while !contains(s,a) s*=randstring(1) end;s)


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Pushy, 20 18 bytes

LFZ^tCN[, ~U'x?i


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The program keeps a stack len(input) characters long, and constantly removes the first and appends a new random char, until the initial input string is reached. Each character is printed as it is added, creating the desired effect.

Explanation:

                      \ == SETUP ==
F                    \ Put input on second stack
L Z^tC                \ On the main stack, make length(input) copies of 0
N               \ Remove printing delimiter (newline by default)

\ == MAIN LOOP ==

[              \ Infinitely:
,             \    Pop the first item on stack
 ~U        \    Add a new random character (between 32 and 126)
'       \    Print this new character
x?     \    If the stacks are now equal:
i    \        Exit program


Brachylog, 17 bytes

I⁰∧Ẹ{sI⁰&|;Ṭṛᵗc↰}


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I⁰                   The global variable I⁰
is the input,
∧                  and
Ẹ                 starting with the empty string
{          ↰}    call this sub-predicate again
ṛ        with a random
Ṭ         printable ASCII character
;  ᵗc      appended to the string we're building
|           unless
I⁰             I⁰ (which is the input)
s               is a substring of the string we've been building
&            in which case the string is output.


Can randomly stack overflow. This makes use of two recently added features in Brachylog: global variables, and the apply-to-tail metapredicate ᵗ.

Pyth, 13 bytes

W!}z=akpOrd\


where the unprintable character is 0x7F.

Test

Bash 94 bytes

p=printf\ -v;until [[ $s = *"$1" ]];do $p x %x$[32+RANDOM%95];$p c \\x$x;s+=$c;done;echo "$s"


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