34
\$\begingroup\$

So, I wrote myself a one-liner which printed out a snake on the console. It's a bit of fun, and I wondered how I might condense my code...

Here's a (short) example output:

                +
                 +
                  +
                   +
                   +
                   +
                  +
                   +
                    +
                    +
                    +
                     +
                     +
                      +
                      +
                       +
                      +
                     +
                     +
                    +

Here's the specs:

  • In each line, a single non-whitespace character (whichever you like) is printed to the console, initially with 29 to 31 spaces padding to the left of it.
  • Each iteration, a random decision is made between these three actions
    • The amount of padding decreases by 1
    • The amount of padding remains the same
    • The amount of padding increases by 1

Do this 30 times, to print 30-segment long a snake to the console.

The shortest answer in bytes wins.

\$\endgroup\$
  • \$\begingroup\$ Can we return an array of lines? Are leading/trailing spaces or newlines allowed? \$\endgroup\$ – Shaggy Feb 20 '18 at 12:07
  • 1
    \$\begingroup\$ I assume trailing spaces on each line are allowed, right? \$\endgroup\$ – Luis Mendo Feb 20 '18 at 13:20
  • 1
    \$\begingroup\$ What does "random" mean? Uniformly random? Random from any distribution with positive support on each of the three outcomes? Random from any distribution whatsoever? Do the results have to be different on each run of the program? \$\endgroup\$ – Nathaniel Feb 21 '18 at 9:02
  • 1
    \$\begingroup\$ Note that, by default, random does not mean uniformly so. For example, the second part of my brainfuck answer is (as of now) perfectly valid, despite it generating a straight line most of the time. \$\endgroup\$ – Jo King Feb 21 '18 at 15:11
  • 1
    \$\begingroup\$ Right now, there are two points that are unclear: 1) Does random mean uniformly random? (affects this answer) and 2) Must the output be different every time? (i.e., can the random number generator be unseeded? Affects this answer) \$\endgroup\$ – DJMcMayhem Mar 2 '18 at 20:41

48 Answers 48

14
\$\begingroup\$

05AB1E, 15 14 bytes

30DF2Ý<+ΩD0sú,

Try it online!

Uses 0.

Explanation

30DF2Ý<+ΩD0sú,
30D            # Push 30 to the stack (One for the amount of iterations we are going to perform and one for the initial padding)
   F           # Pop one of the 30s and perform the following that many times...
    2Ý          # Push [0,1,2] ...
      <         # and create [-1,0,1] from that
       +        # Add the last padding to every entry (e.g. 30 in the beginning resulting in [29,30,31]
        Ω       # Pick one of the results at random ...
         D      # and push it to the stack twice
          0     # Push 0 (Any character will work fine here) ...
           sú   # and pad it with the randomly chosen amount of spaces in the front
             ,  # Finally print the result with a trailing newline
\$\endgroup\$
14
\$\begingroup\$

Random Brainfuck, 123 122 121 bytes

+[--[<]>>+<-]>+[->+>+>+<<<]++++++++++>>++<[>>[->+<<.>]>[-<+>]>?>+++<[>->+<[>]>[<+>-]<<[<]>-]>-->,<[-<<<+>>>]<<<<+.-<<.>-]

Try it online!

Random Brainfuck is an extension of brainfuck, with the helpful addition of the ? command, which sets the current cell to a random byte. This prints a snake made of !s, which looks more like footsteps than a snake funnily enough.

How It Works:

+[--[<]>>+<-]>+ Create the value 30
[->+>+>+<<<]    Copy it three times
++++++++++      Create a newline cell
>>++<            Adds 2 to the second copy to make it a space and move to the counter
[ While counter
  >>[->+<<.>]>[-<+>] Print out the padding cell number of spaces
  ?>+++<[>->+<[>]>[<+>-]<<[<]>-] Get 3-(random byte%3)
  >-->,<[-<<<+>>>]   Add (result-2) to the padding cell
  <<<<+.-<           Print an exclamation mark
  <<.                Print a newline
  >-                 Decrement counter
] end loop

Another solution that sticks to the letter of the question, rather than the spirit.

87 bytes

+[--[<]>>+<-]>+[->+>+>+<<<]++++++++++>++>[>[->+<<<.>>]>[-<+>]?[,<+>]?[,<->]<<<+.-<.>>-]

Try it online!

This one is heavily biased towards leaving the padding alone, but increasing or decreasing the padding are both equally possible. Each one has a slightly less than 1 in 256 chance to happen.

\$\endgroup\$
  • \$\begingroup\$ Very nice! I was unaware of the ? command. +1 \$\endgroup\$ – Grant Miller Feb 23 '18 at 16:39
  • \$\begingroup\$ @GrantMiller ? is only available in Random Brainfuck, not classic brainfuck \$\endgroup\$ – Jo King Feb 23 '18 at 23:01
8
\$\begingroup\$

C (gcc), 61 58 56 bytes

Answer edited to reflect rules changes...

i;f(s){for(s=i=31;--i;printf("%*d\n",s+=1-rand()%3,8));}

Try it online!

\$\endgroup\$
  • \$\begingroup\$ save a byte by moving s+=1-rand()%3 to the printf function. i;f(s){for(s=i=31;--i;)printf("%*c\n",s+=1-rand()%3,43);} \$\endgroup\$ – Vaelus Feb 21 '18 at 2:37
  • \$\begingroup\$ @Vaelus That makes the first line have a varying amount of spaces instead of the 30 specified in the question. \$\endgroup\$ – Steadybox Feb 21 '18 at 7:52
  • \$\begingroup\$ @Steadybox Which is allowed in the comments apparently.. \$\endgroup\$ – Kevin Cruijssen Feb 21 '18 at 8:03
7
\$\begingroup\$

Retina, 24 bytes


30* +
-29{¶<`^
 
S,2@1`

Try it online!

Explanation


30* +

Initialise the working string to the first line, i.e. 30 spaces and a +.

-29{¶<`^
 

There's a space on the second line. -29{ wraps the remainder of the program in a loop, which is run 29 times. ¶< prints the working string at the beginning of each loop iteration with a trailing linefeed. The atomic stage itself inserts a space at the beginning of the string (the basic idea is to insert one space, and then randomly remove 0–2 spaces, because that's a byte shorter than randomly choosing between deletion, inserting and no-op).

S,2@1`

This matches the empty regex against the input, which gives us every position between characters (and the start and end of the string). Then ,2 keeps only the first three matches, i.e. the matches after zero, one and two spaces. @ selects a random one of those three matches. Then the split stage (S) splits the input around that match. And the 1 tells it to keep only the second part of the split. In other words, we discard everything up to our random match.

The 30th line, which is the result of the final loop iteration, is printed implicitly at the end of the program.

\$\endgroup\$
  • \$\begingroup\$ You know what's even shorter than removing 0--2 spaces? Shuffling spaces around!. By the way, the new Retina is great :D \$\endgroup\$ – Leo Feb 22 '18 at 5:48
7
\$\begingroup\$

VBA, 60 59 49 Bytes

For l=1To 30:?Spc(30+i)"+":i=i+Sgn(Rnd()-.5):Next

Paste it in the Immediate window and hit enter. (Make sure explicit declaration is turned off!)

Far more likely to move than to stay in a line (i.e. actions are not equally weighted) but that was not a specified requirement (Fortunately!)

{EDIT} Saved 1 byte by removing the space between =1 and To

{EDIT2} Saved 10 bytes thanks to remoel's comment

Old Versions:

'V1
i=30:For l=1 To 30:?String(i," ")&"+":i=i+Sgn(Rnd()-.5):Next
'V2
i=30:For l=1To 30:?String(i," ")&"+":i=i+Sgn(Rnd()-.5):Next
\$\endgroup\$
  • 5
    \$\begingroup\$ Welcome to PPCG! \$\endgroup\$ – Martin Ender Feb 20 '18 at 14:53
  • 2
    \$\begingroup\$ You can save a few bytes by replacing String(i," ") to Spc(30+i) then remove i=30: . Or -1 byte by removing & . :) \$\endgroup\$ – remoel Feb 21 '18 at 5:28
7
\$\begingroup\$

C# (.NET Core), 112 110 106 100 99 98 bytes

v=>{var r="";for(int t=30,i=t;i-->0;r+="+\n".PadLeft(t+=new System.Random().Next(3)-1));return r;}

-1 byte thanks to @raznagul.
-1 byte thanks to @auhmaan.

Explanation:

Try it online.

v=>{                      // Method with empty unused parameter and no return-type
  var r="";               //  Result-string, starting empty
  for(int t=30,           //  Temp-integer, starting at 30
      i=t;i-->0;          //  Loop 30 times
    r+=                   //   Append the result-String with:
       "+\n"              //    The character and a new-line,
            .PadLeft(     //    left-padded with `t` spaces,
                     t+=new System.Random().Next(3)-1));
                          //    after `t` first has been changed with -1, 0, or 1 randomly
  return r;}              //  Return the result-string
\$\endgroup\$
  • \$\begingroup\$ One strange thing: If I call new Random().Next() multiple times locally (.net Framework Version 4.6.1) I always get the same result. I need to add a Thread.Sleep(10) between the call to reliably get different results. With a sleep time of less than 10ms I sometimes still get the same result. So .net-Framework and TIO (.net-Core) have different PRNGs or at least use different seeds. If I switch your program in TIO to C#-mono I get the same behavior as I get locally in .net-Framework. \$\endgroup\$ – raznagul Feb 20 '18 at 13:26
  • \$\begingroup\$ @raznagul Hmm, that output with C# (Mono C# compiler) is indeed weird.. \$\endgroup\$ – Kevin Cruijssen Feb 20 '18 at 13:30
  • 3
    \$\begingroup\$ @raznagul new Random() uses the time as the seed so in a tight loop the time is the same and so the result is the same. \$\endgroup\$ – TheLethalCoder Feb 20 '18 at 15:28
  • \$\begingroup\$ @TheLethalCoder: Yes, that is what I (more or less) expected. The strange things are that 1) .net-Core (at least on TIO) behaves differently. 2) That I need Thread.Sleep(10) to reliably get different results and Thread.Sleep(1) or even 9ms is not enough. \$\endgroup\$ – raznagul Feb 20 '18 at 15:33
  • \$\begingroup\$ @raznagul Well sleeping for 1, 9 or 10ms should all sleep for the same time depending on other processes running... odd indeed. \$\endgroup\$ – TheLethalCoder Feb 20 '18 at 15:37
7
\$\begingroup\$

C, 56 bytes

n;f(p){n>29?n=0:f(printf("%*d\n",n++?p-rand()%3:31,0));}

Try it online!

Explanation:

n; // As a global variable, n is initialized to zero.
f(p)
{
    // Call the function recursively until n > 29.
    n > 29

        // At the end, set n back to zero.
        ? n=0

        // On the first iteration, n == 0 and p has an indeterminate value.
        // 'n++ ? p-rand()%3 : 31' returns 31 (without reading p), and thus
        // 30 spaces get printed. printf() returns the number of characters
        // printed, 32 (30 spaces + '0' + '\n').
        //    On subsequent iterations, p has the value the previous printf
        // call returned, which is the padding on last iteration + 2. Also,
        // n > 0, so the same expression now returns p-rand()%3, and thus
        // the padding changes either by -1, 0, or 1 spaces. The function
        // is again called with the value of the current line's padding + 2.
        : f(printf("%*d\n", n++ ? p-rand()%3 : 31, 0));
}

C (gcc), 55 bytes

n;f(p){n=n<30&&f(printf("%*d\n",n++?p-rand()%3:31,0));}

Depends on f "returning" the value assigned to n in the function, which is undefined behaviour, but works consistently with gcc when no optimizations are enabled.

Try it online!

\$\endgroup\$
6
\$\begingroup\$

JavaScript (ES8), 63 62 60 bytes

Includes a trailing newline. *2-1 could be replaced with -.5 for a 1 byte saving but the chances of each line being the same length as the previous line would be greatly increased. Of course, as "random" isn't defined in the challenge, the RNG could be replaced with new Date%3-1 for a total byte count of 55.

f=(x=y=30)=>x?``.padEnd(y+=Math.random()*2-1)+`+
`+f(--x):``

Saved a byte thanks to someone who deleted their comment before I could catch the name. I'd actually tried it this way with repeat and padStart but didn't think to try padEnd - don't know why!

o.innerText=(
f=(x=y=30)=>x?``.padEnd(y+=Math.random()*2-1)+`+
`+f(--x):``
)()
<pre id=o>


Bonus

For the same number of bytes, here's a version that takes the number of starting spaces & iterations as input.

f=(x,y=x)=>x?``.padEnd(y)+`+
`+f(--x,y+Math.random()*2-1):``

o.innerText=(
f=(x,y=x)=>x?``.padEnd(y)+`+
`+f(--x,y+Math.random()*2-1):``
)(i.value=30);oninput=_=>o.innerText=f(+i.value)
<input id=i type=number><pre id=o>

\$\endgroup\$
  • \$\begingroup\$ f=(x=y=30)=>x?`+\n`.padStart(y+=Math.random()*2-1)+f(--x):`` is one byte shorter. (Note: Since SO doesn't allow line breaks in comments, I had to type \n instead of actually using a line break.) \$\endgroup\$ – Stefnotch Feb 20 '18 at 18:52
  • \$\begingroup\$ Thanks, @Stefnotch. Unfortunately, even with an initial value of y=31, there would be a possibility of the first line being too short. tio.run/##BcFLDsIgEADQvSeZkUCs7kzQE7hyqSYzKfRjKBCYGHp6fO/… \$\endgroup\$ – Shaggy Feb 20 '18 at 19:01
  • 1
    \$\begingroup\$ Correct me if I'm wrong, but doesn't your current solution also suffer from that issue? \$\endgroup\$ – Stefnotch Feb 21 '18 at 20:55
  • 1
    \$\begingroup\$ The first line should have exactly 30 spaces, according to the challenge. \$\endgroup\$ – Nit Feb 23 '18 at 13:34
  • 1
    \$\begingroup\$ @Nit, the OP has confirmed that the first line may contain 29-31 spaces but has yet to edit that fact into the challenge, despite repeated requests to do so. \$\endgroup\$ – Shaggy Feb 23 '18 at 13:45
6
\$\begingroup\$

Java 8, 89 87 bytes

First golf, I'm sure it could be much better..

Edit: Fixed first line thanks to Steadybox.

l->{for(int a=31,b=a;--a>0;){System.out.printf("%"+b+"c\n",'+');b+=2-Math.random()*3;}}

Try it online!

 l->{                                           //Begin lambda
    for(int a=31,b=a;--a>0;)                  //Initialise vars, loop through 30 lines
    {
        System.out.printf("%"+b+"c\n",'+');     //Print result
        b+=2-Math.random()*3;                   //Change padding by -1, 0, or 1
    }
\$\endgroup\$
  • 5
    \$\begingroup\$ Welcome to PPCG! :) \$\endgroup\$ – Shaggy Feb 20 '18 at 22:27
  • 2
    \$\begingroup\$ 83 bytes \$\endgroup\$ – Steadybox Feb 20 '18 at 22:43
6
\$\begingroup\$

Python 2 , 83 65 64 bytes

Straightforward approach:

import os
k=30
exec"print' '*k+'+';k+=ord(os.urandom(1))%3-1;"*k

Try it online!

Thanks to @Rod for saving some bytes! Thanks to @ovs for -1 byte!

Edit: changed variable name and output string to the letter 's'

More snake-like output for 88 bytes:

from random import*
s=[30,0]
exec"print' '*sum(s)+'(S)'[s[-1]+1];s+=[randint(-1,1)];"*30
\$\endgroup\$
  • 1
    \$\begingroup\$ I like this. Really neat solution. \$\endgroup\$ – healeycodes Feb 20 '18 at 14:01
6
\$\begingroup\$

APL (Dyalog), 20 bytes

1 byte saved thanks to ngn

↑'+'↑⍨¨-+\30,2-?29⍴3

Try it online!

\$\endgroup\$
  • \$\begingroup\$ ¯2+ ---> 2- \$\endgroup\$ – ngn Feb 20 '18 at 12:23
5
\$\begingroup\$

Charcoal, 14 bytes

× ³⁰F³⁰«↙+M‽³→

Try it online! Link is to verbose version of code. Explanation:

× ³⁰            Print 30 spaces (forces the desired indentation)
    F³⁰«        Repeat 30 times
        ↙+      Print a `+` and move down and left one square
          M‽³→  Move right a random number of squares from 0 to 2

Would be only 10 bytes if there was no initial indentation requirement.

\$\endgroup\$
  • \$\begingroup\$ @KevinCruijssen Hmm, that's awkward, because Charcoal likes to trim by default. \$\endgroup\$ – Neil Feb 20 '18 at 12:26
5
\$\begingroup\$

PHP, 61 bytes

for($p=32;$i<30;$i++)echo str_pad("+
",$p+=rand(-1,1),' ',0);

Try it online!

\$\endgroup\$
  • 8
    \$\begingroup\$ $i<30;$i++ can be $i++<30; to save 2 bytes. \$\endgroup\$ – Kevin Cruijssen Feb 20 '18 at 13:44
  • 2
    \$\begingroup\$ 55 bytes: for($p=30;$i++<30;$p+=rand(-1,1))printf("%{$p}s\n",'+'); (the \n is counted as 1 char, and should be replaced by a real newline) \$\endgroup\$ – Ismael Miguel Feb 23 '18 at 15:37
  • 2
    \$\begingroup\$ Alternative 55-byte long, without warnings: for($i=$p=30;$i--;$p+=rand(-1,1))printf("%{$p}s\n",'+'); \$\endgroup\$ – Ismael Miguel Feb 23 '18 at 15:41
5
\$\begingroup\$

Java 8, 131 129 127 126 119 108 101 bytes

v->{String r="";for(int i=30,j,t=i;i-->0;r+="+\n")for(j=t+=Math.random()*3-1;j-->0;r+=" ");return r;}

Explanation:

Try it online.

v->{                     // Method with empty unused parameter and String return-type
  String r="";           //  Result-String, starting empty
  for(int i=30,j,t=i;    //  Two index integers, and a temp integer (starting at 30)
      i-->0;             //  Loop 30 times:
      r+="+\n")          //    After every iteration: Append the character and a new-line
    for(j=t+=Math.random()*3-1;
                         //   Change `t` with -1, 0, or 1 randomly
        j-->0;r+=" ");   //    And append that many spaces to the result-String
  return r;}             //  Return the result-String

Old 119 byte answer:

v->{String s="",r=s;int i=90,t=30;for(;i-->t;s+=" ");for(;i-->0;t+=Math.random()*3-1)r+=s.substring(t)+"+\n";return r;}

Explanation:

Try it online.

v->{                      // Method with empty unused parameter and String return-type
  String s="",            //  Temp-String, starting empty
         r=s;             //  Result-String, starting empty
  int i=90,t=30;          //  Temp integer, starting at 30
  for(;i-->t;s+=" ");     //  Fill the temp String with 60 spaces
  for(;i-->0;             //  Loop 30 times:
      t+=Math.random()*3-1//    After every iteration: Change `t` with -1, 0, or 1 randomly
    r+=s.substring(t)     //   Append the result with `60-t` amount of spaces
       +"+\n";            //   + the character and a new-line
  return r;}              //  Return the result-String
\$\endgroup\$
4
\$\begingroup\$

R, 72 69 67 bytes

cat(sprintf(paste0("% ",cumsum(c(30,sample(3,29,T)-2)),"s"),"+\n"))

Thanks to Zahiro Mor for 2 extra bytes!

Try it online!

\$\endgroup\$
  • \$\begingroup\$ Switching from sample(3,29,T)-2 to runif(29,-1,1) will reduce byte count by 2 but moves are not equally likely anymore. And could you also switch to paste("%" instead of paste0("% " or am I missing something here? \$\endgroup\$ – Rift Feb 20 '18 at 16:45
  • \$\begingroup\$ @Rift if i was using paste the resulting strings would be of the form % 30 s instead of % 30s. As you said runif would mess up the probabiities. \$\endgroup\$ – plannapus Feb 20 '18 at 17:46
  • \$\begingroup\$ Locally sprintf("%30s"), sprintf("% 30s") and sprintf("% 30 s") return the same results for me. But on TIO only the first two have identical results, so paste0("%" should save a byte. And there is no requirement that every move has the same probability. \$\endgroup\$ – Rift Feb 21 '18 at 12:41
4
\$\begingroup\$

Japt, 13 bytes

Returns an array of lines.

30ÆQù1nH±1n3ö

Test it


Explanation

30Æ               :Create the range [0,30) and pass each through a function
   Q              :  The " character
    ù             :  Pad start to length...
           3ö     :    Random element from the range [0,3)
         1n       :    Subtract 1
       H±         :    Add the result of that to H (inititally 32)
     1n           :    Subtract 1 to avoid the possibility of the first line being 33 characters long in total

Bonus

For 2 bytes less, here's a version that takes the number of starting spaces & iterations as input.

U°ÆQùU±1n3ö

Try it


Alternative RNGs

The last 4 bytes can be replaced with any of the following:

MrJ1     :A random float between -1 and 1
Jõ ö     :Generate the range [-1,1] and return a random element
3ö É     :An alternative way of writing the method used above
½nMr     :0.5 subtracted from a random float between 0 and 1
\$\endgroup\$
  • 1
    \$\begingroup\$ Wow, can't believe we're winning at the moment! I think you can save a byte with this (on mobile so I can't really verify) \$\endgroup\$ – ETHproductions Feb 20 '18 at 13:52
  • \$\begingroup\$ @ETHproductions: Ha! That's identical to what I started out with. The problem is, though, if -1 is returned by the RNG on the first iteration, we'll end up with a total line length of 29 when it should be 30, 31 or 32. \$\endgroup\$ – Shaggy Feb 20 '18 at 13:55
  • \$\begingroup\$ Hmm, I'm confused about how your version gets around that then... Also, I believe OP has clarified in the comments that they don't care if an extra space is removed or added in the initial iteration. \$\endgroup\$ – ETHproductions Feb 20 '18 at 13:59
  • \$\begingroup\$ Actually I'm confused by "when it should be 30, 31, or 32"—where is that required? \$\endgroup\$ – ETHproductions Feb 20 '18 at 14:01
  • \$\begingroup\$ @ETHproductions: We start with 30 and then add -1, 0 or 1 giving us 29, 30 or 31 - add the " and that gives us a total length of 30, 31 or 32 for the first line. \$\endgroup\$ – Shaggy Feb 20 '18 at 14:04
4
\$\begingroup\$

Swift, 101 bytes

import UIKit
var g=29;for _ in 0...g{print((0..<g).map{_ in" "}.joined(),0);g+=Int(arc4random()%3)-1}

Explanation

A full program. This uses a rather odd trick: arc4random() is a member of the Darwin module, but UIKit also comes with this function installed, so it saves a byte :) Also uses one of my Swift golfing tips for repeating strings an arbitrary number of times.

import UIKit        // Imports the UIKit module, necessary for the RNG.
var g=29;           // Declares an integer variable g by assigning it to 30.
for _ in 0 ... g {  // Execute the code block 30 times (for each integer in [0; g]):
 print(             // Output the following:
  (0..<g).map       // For each integer in [0; g)...
   {_ in" "}        // ... return a literal space character. 
    .joined()       // ... And join the result to a single string.
             ,0     // Also print a "0" preceded by a single space (g starts from 29).
 );
g+=                 // Increment the variable g by...
   arc4random()%3   // ... A random integer, modulo 3...
   Int(...)-1       // ... Casted to an integer (yes, this is needed!) and decremented.
}
\$\endgroup\$
  • \$\begingroup\$ Doesn't for _ in 0 ... g execute the code block 29 times now instead of 30 (loop from 0 to 29 (exclusive))? \$\endgroup\$ – Kevin Cruijssen Feb 20 '18 at 16:21
  • \$\begingroup\$ @KevinCruijssen No, 0...g generates all the integers in [0; g]. My bad, fixed the explanation. 0..<g would generate the integers in [0; g) :P \$\endgroup\$ – Mr. Xcoder Feb 20 '18 at 16:22
  • \$\begingroup\$ Ah, the [0; g) you've edited to [0; g] indeed confused me. :) Hmm, but isn't it possible to start at g=30 and loop [1; g] in that case? \$\endgroup\$ – Kevin Cruijssen Feb 20 '18 at 17:55
  • \$\begingroup\$ @KevinCruijssen Looping over either [0; g) or [1; g] would definitely be possible if I choose g=30 instead, but then print(...,0) needs to be changed to print(...+"0"), because an additional (extraneous) space would be prepended before the 0 otherwise. Either way, the byte count remains the same. \$\endgroup\$ – Mr. Xcoder Feb 20 '18 at 17:58
4
\$\begingroup\$

Perl, 36 bytes

perl -E '$#a=29;map{$#a+=rand(3)-say"@a -"}@a'
\$\endgroup\$
  • \$\begingroup\$ So good. I always forget you can set an array length like that... and using say for subtraction. Am I right in thinking it doesn't change the number of runs when $#a is incremented because it's not a reference? \$\endgroup\$ – Dom Hastings Feb 20 '18 at 16:38
  • \$\begingroup\$ @DomHastings: It's because I use map which seems to first lay out the elements on the stack. for does not and would have had an unpredictable loop length \$\endgroup\$ – Ton Hospel Feb 20 '18 at 18:11
  • \$\begingroup\$ That's really useful to know. Thanks! \$\endgroup\$ – Dom Hastings Feb 20 '18 at 19:54
  • \$\begingroup\$ Nice golfing. I tried to shave off another byte with perl -E 'map{$#a+=rand(3)-say"@a -"}@a=1..30', but that sometimes (not every time) resulted in segmentation fault. Could it be a bug in perl v5.22.1 and v5.16.3? \$\endgroup\$ – Kjetil S. Feb 21 '18 at 16:49
  • \$\begingroup\$ @Kjetil Yes, that is a well known problem that probably will never be fixed. When looping an array the entries don't get an extra refcount, so if you delete them they are freed by the time the loop reaches them and you hit freed memory. Fortunately you never do this in real programs. \$\endgroup\$ – Ton Hospel Feb 21 '18 at 18:20
4
\$\begingroup\$

R, 54 53 bytes

cat(sprintf('
%*s',cumsum(c(30,sample(3,29,T)-2)),0))

Similar idea as above, but with shortened sprintf code and a shorter character string literal. Instead of \n (two bytes) I’m using a literal line break (one byte).

Try it online!

\$\endgroup\$
  • \$\begingroup\$ A field width or precision (but not both) may be indicated by an asterisk *: in this case an argument specifies the desired number. I've been using sprintf for years and somehow always missed that part... Thanks for the reminder! \$\endgroup\$ – plannapus Feb 20 '18 at 18:51
  • 1
    \$\begingroup\$ The second line is sometimes indented two spaces instead of one. \$\endgroup\$ – Scott Milner Feb 21 '18 at 5:18
  • \$\begingroup\$ @ScottMilner Found some time to fix it. \$\endgroup\$ – Konrad Rudolph Feb 21 '18 at 14:54
4
\$\begingroup\$

Ruby, 45 39 bytes

x=30
x.times{puts' '*(x+=rand(3)-1)+?S}

Try it online!

Modifying x during the loop does not affect the loop counter. I chose S as a particularly snakelike output character.

-6 bytes: Use rand(3)-1 instead of [-1,0,1].sample. Thanks, Eric Duminil!

\$\endgroup\$
  • \$\begingroup\$ You can save two bytes with x.map instead of x.times (equivalent since you don't use the return value) \$\endgroup\$ – RJHunter Feb 21 '18 at 2:11
  • 1
    \$\begingroup\$ Oops, you're right, ignore me! \$\endgroup\$ – RJHunter Feb 21 '18 at 3:34
  • 1
    \$\begingroup\$ OK I've got a better one: rand -1..1 is five bytes shorter than [-1,0,1].sample \$\endgroup\$ – RJHunter Feb 21 '18 at 4:36
  • 1
    \$\begingroup\$ @RJHunter: Or rand(3)-1 for 6 bytes less. \$\endgroup\$ – Eric Duminil Feb 21 '18 at 7:52
  • 1
    \$\begingroup\$ (x=30).times{puts' '*x+?+;x+=rand(3)-1} (same size) will print exactly 30 spaces for the head of the snake as requested by the challenge \$\endgroup\$ – Asone Tuhid Feb 28 '18 at 9:54
4
\$\begingroup\$

SenseTalk, 237 198 Bytes

This is a language that I came to know and love about a decade ago. It's the scripting language that drives the automated testing tool Eggplant Functional. I was an avid user of the tool for many years before joining the company for a while. It's not the most golf-capable language, but I find it very enjoyable to write in. Golfing in it is actually quite challenging as the language is meant to be verbose and English-like... took me quite a while to get it down to 237 bytes.

set s to "                              +"&lf
set p to s
repeat 30
set a to random(0,2)
if a equals 0
delete first char of p
else if a equals 1
put " " before p
end if
put p after s
end repeat
put s

Ungolfed/Explanation

set the_snake to "                              +"&lf #assign the first line of the snake
set previous_line to the_snake                        #set up for the loop

repeat 30 times                                       #loop 30x
    set action to random(0,2)                         #random add/subtract/stay the same

    if action equals 0
        delete the first character of previous_line   #SenseTalk really shines at string manipulation
    else if action equals 1
        put " " before previous_line                  #insert a character at the beginning
    end if

    put previous_line after the_snake                 #plop the new segment into the string
end repeat                                            #close the loop

put the_snake                                         #print to standard out

Edit: Saved 36 bytes thanks to @mustachemoses

\$\endgroup\$
  • 1
    \$\begingroup\$ Is the whitespace necessary? \$\endgroup\$ – MustacheMoses Feb 27 '18 at 5:52
  • \$\begingroup\$ I've a lot of respect for this. Particularly against the background of 'golfing languages' which seem to exist to be utterly unreadable, but short. It's nice to have an example that's just showing what you can do with your language. \$\endgroup\$ – AJFaraday Feb 27 '18 at 9:11
  • 1
    \$\begingroup\$ Good call @MustacheMoses! Updated. \$\endgroup\$ – Allen Fisher Feb 28 '18 at 4:17
  • \$\begingroup\$ I count 198 bytes (well, the userscript counts that many) \$\endgroup\$ – HyperNeutrino Feb 28 '18 at 5:16
  • \$\begingroup\$ @AllenFisher Do you have a standalone interpreter or compiler for this language that I can use without getting a Eggplant demo? \$\endgroup\$ – MustacheMoses Feb 28 '18 at 18:15
3
\$\begingroup\$

J, 23 bytes

echo(8":~+/)\31,1-?29$3

Try it online!

\$\endgroup\$
3
\$\begingroup\$

PowerShell, 42 bytes

1..($l=30)|%{" "*$l+"x";$l+=-1,0,1|Random}

Try it online!

Loops from 1 to $l=30. Each iteration we put $l spaces plus an x onto the pipeline as a string, then += either of -1, 0, 1 based on Get-Random into $l for the next loop. Those strings are gathered from the pipeline and an implicit Write-Output gives us a newline-separated list for free.

\$\endgroup\$
3
\$\begingroup\$

Bash, 53

  • 3 bytes saved thanks to @Dennis
for((i=p=30;i--;p+=RANDOM%3-1));{ printf %${p}s+\\n;}

Try it online.

\$\endgroup\$
  • \$\begingroup\$ p+=RANDOM%3-1 works too. \$\endgroup\$ – Dennis Feb 20 '18 at 18:47
  • \$\begingroup\$ @Dennis Yes of course! Thanks! \$\endgroup\$ – Digital Trauma Feb 20 '18 at 19:35
3
\$\begingroup\$

Jelly, 18 bytes

1ŒRX+
30ǒС⁶ẋ;€0Y

Try it online!

The chosen character is 0. If returning a list of list of characters is allowed, then the Y can be dropped and the submission can be turned into a niladic chain for 17 bytes. Alternative.

How it works

30ǒС⁶ẋ;€0Y | Niladic main link.
30           | Starting from 30...
  ǒС       | ... Repeat the helper link 29 times and collect the results in a list.
             | (This list includes the first 30, so there are actually 30 numbers).
      ⁶ẋ     | Repeat a space that many times, for each item in the list.
        ;€0  | Append a 0 to each.
           Y | And join by newlines.
-------------+
1ŒRX+        | Monadic helper link. Alternatively, you can use µ1ŒRX+µ instead of the Ç.
1            | The literal one.
 ŒR          | Symmetric range from –1 to 1.
   X+        | Choose a random number therein and add it to the argument.

Jelly, 16 bytes

Combining mine, Erik’s and Jonathan’s solutions, we can golf this down to 16 bytes. The chosen character is 1.

’r‘X
30ǒСṬ€o⁶Y

Try it online!

Thanks to Jonathan Allan for the heads-up (on Ṭ€o⁶).

\$\endgroup\$
  • \$\begingroup\$ You could use Ṭ€o⁶ in place of ⁶ẋ;€0 like my 18 byter does and get to down to 17. \$\endgroup\$ – Jonathan Allan Feb 21 '18 at 1:00
  • \$\begingroup\$ @JonathanAllan Thank you! Combining the three Jelly answers, I actually ended up having 16 bytes. But I posted that as a secondary solution because it is not entirely mine. :-) \$\endgroup\$ – Mr. Xcoder Feb 21 '18 at 5:16
3
\$\begingroup\$

Octave, 53 51 50 49 bytes

printf('%*d\n',[a=31+cumsum(randi(3,1,30)-2);~a])

Try it online!

Saved 1 byte by no longer doing any looping. Saved another as Octave has printf as well as fprintf.

This new code creates an array of 30 random integers in the range -1:1. It then cumulatively sums the array and adds 30, which gives the desired sequence.

The result is printed using fprintf with a format that says "A decimal number, padded to a specified width, followed by a new line. The width will be the first value input, and the decimal number will be the second value input. If the number of values input is more than this, Octave will keep repeating the print automatically to get the desired output.

To achieve the looping then, we need only interleave zeros between the sequence array so the fprintf function uses each value in the sequence as a width, and each zero as the digit to be printed.

Prints an output like:

                              0
                             0
                              0
                             0
                              0
                               0
                              0
                               0
                              0
                              0
                             0
                            0
                           0
                           0
                           0
                          0
                           0
                            0
                             0
                              0
                              0
                             0
                             0
                              0
                               0
                              0
                              0
                               0
                               0
                                0

The above code doesn't always print exactly 30 spaces on the first line. It will be either 29, 30, or 31. To correct that, you would use this 53 byte version:

x=31;for i=2:x;fprintf('%*d\n',x,0);x+=randi(3)-2;end
\$\endgroup\$
  • \$\begingroup\$ You can save two bytes: x=31;for i=2:x;fprintf('%*d\n',x+=randi(3)-2,0);end \$\endgroup\$ – Kevin Cruijssen Feb 21 '18 at 9:11
  • \$\begingroup\$ @KevinCruijssen I thought about that, but it doesn't work the same. It would result in the first line starting with either 29, 30, or 31 spaces. \$\endgroup\$ – Tom Carpenter Feb 21 '18 at 9:13
  • 1
    \$\begingroup\$ @KevinCruijssen in fact, never mind. I've just noticed the OPs comments saying that is allowed. \$\endgroup\$ – Tom Carpenter Feb 21 '18 at 9:14
  • \$\begingroup\$ Yep. It's a bit annoying a rule is in the comment (especially since it contradicts with the current challenge description..). I've asked OP to edit the challenge to reflect you can start with 29, 30 or 31, since he seems to allow it in the comments. \$\endgroup\$ – Kevin Cruijssen Feb 21 '18 at 9:19
3
\$\begingroup\$

Lua, 81 75 bytes

n=30;for i=1,n do print(("%-"..n.."s+"):format(" "))n=n-2+math.random(3)end

In for i=1,n ... the to_exp n is evaluated only once before entering the loop, saving one byte.

-6 thanks to @user202729

Try it online!

\$\endgroup\$
  • 1
    \$\begingroup\$ Welcome to PPCG! You may want to add a TIO link to your post so people can test your program more easily. \$\endgroup\$ – user202729 Feb 26 '18 at 15:53
  • \$\begingroup\$ You can golf your answer down to 76 bytes. Besides the page Tips for golfing in Lua may be useful. \$\endgroup\$ – user202729 Feb 26 '18 at 15:54
  • \$\begingroup\$ 75 bytes. \$\endgroup\$ – user202729 Feb 26 '18 at 15:58
3
\$\begingroup\$

Python 3.6, 84 73 69 bytes

from random import*
x=30
exec("print(' '*x+'+');x+=randint(-1,1);"*x)

Thanks to @WheatWizard for -11 bytes. Thanks to @JoKing for -4 bytes.

\$\endgroup\$
  • \$\begingroup\$ Since you don't end up using i you can use for i in[1]*30 instead to save bytes. \$\endgroup\$ – Sriotchilism O'Zaic Feb 23 '18 at 6:31
  • \$\begingroup\$ You can also from random import* so that you don't need the random. later on. And you can remove the newline space after your :. \$\endgroup\$ – Sriotchilism O'Zaic Feb 23 '18 at 6:32
  • \$\begingroup\$ And if you change 30 to 29 the "+".rjust(x) can be replaced with " "*x+"+". \$\endgroup\$ – Sriotchilism O'Zaic Feb 23 '18 at 6:35
  • \$\begingroup\$ Actually regarding my last comment it should be 30 spaces not 29. Your current answer only puts 29 spaces and thus fails to meet the spec. This can be fixed by changing 30 to 31. \$\endgroup\$ – Sriotchilism O'Zaic Feb 23 '18 at 6:59
  • 1
    \$\begingroup\$ @WheatWizard Thanks! I've added your changes and credited you as well. I changed [1]*30 to [1]*x because it's one byte shorter. \$\endgroup\$ – MustacheMoses Feb 23 '18 at 19:32
3
\$\begingroup\$

ES5, 97 95 81 bytes

for(p=i=30;i--;)console.log(Array(p).join(" ",r=Math.random()*3|0,p+=r>1?-1:r)+0)

ES5, 112 98 bytes if function format is needed:

function a(){for(p=i=30;i--;)console.log(Array(p).join(" ",r=Math.random()*3|0,p+=r>1?-1:r)+0)}a()

\$\endgroup\$
  • 2
    \$\begingroup\$ Welcome to PPCG! I think your variables have to be declared inside of a function - _=>{p=30;for(i=0;i<p;i++){console.log(Array(p).join(" ")+"+\n");r=~~(Math.random()*3);p+=r==2?-1:r}} \$\endgroup\$ – Oliver Feb 23 '18 at 16:37
  • \$\begingroup\$ That'll kill the bytes, I'll tell you that. ES5 doesn't include the arrow functions by default. I'll update \$\endgroup\$ – Kyle Fairns Feb 23 '18 at 16:46
  • \$\begingroup\$ @Oliver, function format added :) \$\endgroup\$ – Kyle Fairns Feb 23 '18 at 16:52
  • \$\begingroup\$ Nice! I'm not sure when it was introduced, but I think you can replace join(" ") with join` ` \$\endgroup\$ – Oliver Feb 23 '18 at 16:54
  • \$\begingroup\$ @Oliver I'm not sure you could do that in ES5, could you? I thought that was a template literal added in ES6? \$\endgroup\$ – Kyle Fairns Feb 23 '18 at 16:56
2
\$\begingroup\$

Red, 54 bytes

loop n: 30[loop n[prin" "]print"+"n: n - 2 + random 3]

Try it online!

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.