Code Golf: Your own horizontal pet ASCII snake

Question

Very heavily inspired by this challenge Code Golf: Your own pet ASCII snake - I thought making it horizontal would add an extra layer of complexity.

An example horizontal snake:

            0 0               
  0        0 0 000            
00 0     00       000 0      0
    000 0            0 0   00 
       0                000   

And the rules are:

1. Exactly 5 lines of characters are printed
2. Each line is exactly 30 characters long, consisting of a combination of spaces and the character you choose to draw your snake with
3. Your snake starts on line 3
4. The next line to be used for drawing your snake must be randomly chosen from your current line, one line above (if you're not already on line 1) or one line below (if you're not already on line 5).
   • These choices must be equally weighted. So if you are on line 1, you have a 50% chance to stay on line 1 and a 50% chance to move to line 2. If you are on line 2, you have a 33% chance to move to line 1, a 33% chance to stay on line 2 or a 33% chance to move to line 3
5. Your snake does not need to visit every single line.

Answer 1

JavaScript (ES6), 98 bytes

Saved 7 bytes thanks to @KevinCruijssen

Returns an array of 5 strings.

f=(y=2,a=[...'  0  '])=>a[0][29]?a:f(y+=(Math.random()*(y%4?3:2)|0)-!!y,a.map((v,i)=>v+=i-y&&' '))

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Commented

f = (                       // given:
  y = 2,                    //   y = current line (0-indexed)
  a = [...'  0  ']          //   a[] = array of 5 lines
) =>                        //
  a[0][29] ?                // if all columns have been processed:
    a                       //   stop recursion and return a[]
  :                         // else:
    f(                      //   do a recursive call with:
      y += (                //     the updated value of y, to which we add -1, 0 or 1:
        Math.random() *     //       pick a random value in [0,1)
        (y % 4 ?            //         if y is neither 0 or 4:
          3                 //             multiply it by 3
        :                   //           else:
          2                 //             multiply it by 2
        ) | 0               //       force an integer value
      ) - !!y,              //     subtract either 0 or 1
      a.map((v, i) =>       //     for each value v at position i in a[]:
        v += i - y && ' '   //       append either '0' if i = y or a space otherwise
      )                     //     end of map()
    )                       //   end of recursive call

Answer 2

Charcoal, 28 bytes

Ｐ|   Ｆ³⁰«0≡ⅉ²Ｍ‽²↑±²Ｍ‽²↓Ｍ⊖‽³↓

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

Ｐ|   

Print some padding to force 5 lines of output.

Ｆ³⁰«

Repeat 30 times.

0

Print a zero (and move horizontally).

≡ⅉ²Ｍ‽²↑

If the Y-coordinate is 2, move up randomly by 0 or 1.

±²Ｍ‽²↓

If it's -2, move down randomly by 0 or 1.

Ｍ⊖‽³↓

Otherwise move down randomly by -1, 0 or 1.

Answer 3

Perl, 68 bytes

perl -E '$%=2;s:$:$n++%5-$%&&$":emg,$%-=!!$%+rand!($%%4)-3for($_=$/x4)x30;say'

This doesn't feel optimal at all.

Answer 4

R, 138 bytes

m=matrix(" ",30,5)
m[1,3]=0
x=3
s=sample
for(i in 2:30)m[i,x<-x+(-1)^(x==5)*s(0:1,1)*x%in%c(1,5)+(s(3,1)-2)*x%in%2:4]=0
write(m,"",30,,"")

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Handily outgolfed by plannapus

Answer 5

Python 3, 144 bytes

@Ruts, @Turksarama, and @mypetlion have been very helpful in reducing bytes

import random
m=[list(' '*30)for y in range(5)]
l=2
for i in range(1,30):
 m[l][i]=0
 l+=random.randint(~-(l<1),l<4)
for j in m:
  print(*j)

Will try and improve on this. Fun challenge!

Answer 6

Jelly, 24 bytes

3µ’o1r‘«5¥$Xµ30СṬ€o⁶z⁶Y

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Explanation

3µ’o1r‘«5¥$Xµ30СṬ€o⁶z⁶Y || Niladic full program.
                         ||
3                        || Starting from 3...
 µ          µ30          || ... Execute 30 times...
               С        || ... And collect the results in a list.
  ’o1r‘«5¥$X             ||--| Monadic "Helper" function.
  ’o1                    ||--| The current integer, decremented OR 1.
     r     X             ||--| Grab a random item from the range from ^ to...
      ‘«5                ||--| ... The number incremented, capped to 5 (uses maximum).
         ¥$              ||--| Syntax elements. Used for grouping links.
                 Ṭ€      || Untruth each.
                   o⁶    || Logical OR with a single space.
                     z⁶  || Transpose with filler spaces.
                       Y || Join by newlines.

Answer 7

R, 120 114 bytes

m=matrix
r=m(" ",30,5)
x=3
for(i in 1:30){r[i,x]=0;x=x+sample(-1:1,1,,m(c(0,rep(1,13)),3)[,x])}
write(r,"",30,,"")

Thanks to @Giuseppe for the additional 6 bytes!

Uses a table of probabilities as follows:

> matrix(c(0,rep(1,13)),3)
     [,1] [,2] [,3] [,4] [,5]
[1,]    0    1    1    1    1
[2,]    1    1    1    1    1
[3,]    1    1    1    1    0
Warning message:
In m(c(0, rep(1, 13)), 3) :
  data length [14] is not a sub-multiple or multiple of the number of rows [3]

where each columns corresponds to a case, i. e. column 1 is picked if the snake is in row 1, giving probabilities 0, 1/2 and 1/2 to pick respectively -1 [go down], 0 [stay still] and 1 [go up] (sample automatically normalize the probabilities to 1), column 2 for row 2 gives probabilities 1/3, 1/3 and 1/3, etc...

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Answer 8

SOGL V0.12, 22 21 bytes

3ā'∑∫⁵╗ž⁴H1ΧGI5χ⁴-ψ+;

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Explanation:

3                      push 3
 ā                     push an empty array - the canvas
  '∑∫                  30 times do, pushing counter            | stack = 3, [], 1
     ⁵                   duplicate the Y coordinate            | stack = 3, [], 1, 3
      ╗ž                 at those coordinates insert "+"       | stack = 3, ["","","+"]
        ⁴                duplicate from below                  | stack = 3, ["","","+"], 3
         H               decrease                              | stack = 3, [...], 2
          1Χ             maximum of that and 1                 | stack = 3, [...], 2
            G            get the item 3rd from top             | stack = [...], 2, 3
             I           increase it                           | stack = [...], 2, 4
              5χ         minimum of that and 5                 | stack = [...], 2, 4
                ⁴-       subtract from the larger a copy of the smaller value | stack = [...], 2, 2
                  ψ      random number from 0 to pop inclusive | stack = [...], 2, 2
                   +     add those                             | stack = [...], 4
                    ;    and get the array back ontop          | stack = 4, ["","","+"]

                         implicitly output the top item - the array, joined on newlines

Answer 9

Japt, 31 29 bytes

Returns an array of lines.

30ÆQùU±[2V=Jõ VVJò]mö i3 gUÃy

Test it

Answer 10

Japt, 26 bytes

30ÆQùU=U?5õ f_aU <2Ãö :3Ãy

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Answer 11

SmileBASIC, 107 105 103 89 bytes

FOR I=0TO 29FOR J=0TO 5LOCATE I,J?" 0"[Y+2==J]NEXT
Y=Y+RND(3)-1D=Y/3>>0Y=Y-D-D*RND(2)NEXT
NEXT

This answer is more interesting than the vertical one because of the (literal) edge cases.

64 bytes, without printing spaces:

FOR I=0TO 29LOCATE,Y+2?0;
Y=Y+RND(3)-1D=Y/3>>0Y=Y-D-D*RND(2)NEXT

I also found a few variations of line 2 with the same length:

Y=Y+RND(3)-1D=Y/3>>0Y=Y-D-D*RND(2)NEXT
Y=Y+RND(3)-1D%=Y/3Y=Y-D%-D%*RND(2)NEXT
Y=Y+RND(3)-1Y=Y-Y DIV 3*(RND(2)+1)NEXT
Y=Y+RND(3)-1Y=Y/3OR.Y=Y-D-D*RND(2)NEXT

The integer division of Y/3 is used to check if Y is outside the valid range, as well as getting the sign.

Answer 12

Python 2, 127 bytes

from random import*
s=['']*5
n=3
r=range(5)
exec"for i in r:s[i]+=' 0'[i==n]\nn=choice(r[n and~-n:n+2])\n"*30
print'\n'.join(s)

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Answer 13

Octave with Statistics Package, 99 bytes

It also works in MATLAB with the Statistics Toolbox.

p=3;for k=1:29
p=[p;p(k)+fix(randsample(setdiff([1 pi 5],p(k)),1)-3)/2];end
disp(['' (p==1:5)'+32])

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Answer 14

Java 8, 177 170 bytes

v->{int a[][]=new int[5][30],c=0,r=2;for(;c<30;r+=Math.random()*(r%4>0?3:2)-(r>0?1:0))a[r][c++]=1;String R="";for(int[]y:a){for(int x:y)R+=x<1?" ":"~";R+="\n";}return R;}

-7 bytes thanks to @OlivierGrégoire.

Explanation:

Try it online.

v->{                // Method with empty unused parameter and String return-type
  int a[][]=new int[5][30],
                    //  Integer-matrix of size 5x30
      c=0,          //  Column, starting at index 0
      r=2;          //  Row, starting at index 2
  for(;c<30;        //  Loop `c` 30 times
      r+=Math.random()*(r%4>0?3:2)-(r>0?1:0))
                    //    After every iteration: change `r` with -1,0,1 randomly
                    //     If `r` is 0: random [0;2)-0 → 0,1
                    //     If `r` is 4: random [0;2)-1 → -1,0
                    //     If `r` is 1,2,3: random [0:3)-1 → -1,0,1
    a[r][c++]=1;    //   Fill the cell at indices `r,c` from 0 to 1
  String R="";      //  Result-String, starting empty
  for(int[]y:a){    //  Loop over the rows of the matrix
    for(int x:y)    //   Inner loop over the individual column-cells of the matrix
      R+=x<1?       //    If the value of the cell is still 0:
          " "       //     Append a space
         :          //    Else (it's 1):
          "~";      //     Append the character
    R+="\n";}       //   After every row, Append a new-line
  return R;}        //  Return the result-String

Answer 15

Japt, 28 bytes

Saved 9 bytes thanks to ETHproductions

3k
29Æp5õ f_aUgY)<2Ãö
¡QùXÃy

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Answer 16

C (gcc), 134 130 bytes

r,x,y=3,a[31],m;f(){for(x=0;x<31;x++){m?putchar(x==30?10:a[x]-m?32:48):(a[x]=y);r=rand();y+=y==1?r%2:y==5?-r%2:1-r%3;}++m<6&&f();}

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Answer 17

Perl, 83 101 bytes

perl -E '$l=3;map{map$s[$_-1].=/$l/?0:" ",1..5;$l-=1-int 3*rand;$l=~y/60/51/}1..30;say for@s'

New: Without probability issue at the borders:

perl -E '$l=3;map{map$s[$_-1].=/$l/?0:" ",1..5;$l=int($l<2?1+2*rand:$l>4?6-2*rand:$l-1+3*rand)}1..30;say for@s'

Ungolfed:

$l=3;                             #start line
map{
  map $s[$_-1].=/$l/?0:" ",1..5;  #0 at current char and line, space elsewhere
  $l-=1-int 3*rand;               #up, down or stay
  $l=int( $l<2 ? 1+2*rand
        : $l>4 ? 6-2*rand
        :        $l-1+3*rand )    #border patrol
}
1..30;                            #position
say for@s                         #output result strings/lines in @s

Answer 18

Scala, 207 Bytes

val b=Array.fill(150)('.')
def s(y:Int,x:Int)={val r=Random.nextInt(6)
val z=y+(if(y>3)-r%2
else if(y<1)r%2
else r/2-1)
b(z*30+x)='$'
z}
(3/:(0 to 28))(s(_,_))
b.mkString("").sliding(30,30).foreach(println)

sample:

...................$$$...$.$$.
.$$$..............$...$.$.$...
$...$$$..$...$$.$$.....$......
.......$$.$.$..$..............
...........$..................

degolfed:

val buf = List.fill(150)('.').toBuffer
def setRowCol (y:Int, x:Int): Int = {
  val r = Random.nextInt(6)
  val z = y + (
    if (y>3) 
        -(r%2)
    else if (y<1) 
        (r%2)
    else 
        r/2-1
  )
  buf (z * 30 + x) = '$'
  z
}
(3 /: (0 to 28)(setRowCol (_, _))
println 
buf.mkString ("").sliding(30,30).foreach(println)

My unique invention - well, I haven't read the other solutions so far, is, to generate a Random (6) which is implicitly two Randoms, (2*3). If away from the border, I use the values of r/2 (0,1,2) and → (-1,0,1) tell me, to go up or down. If at the border, I can avoid the character costly call of another random, and just take the modulo(2), to decide, should I stay or should I go.

Let's see the other solutions. :)

Answer 19

Ruby, 98 77 bytes

->{a=(0..4).map{" "*30}
x=2
30.times{|i|a[x][i]=?@
x+=rand(3-17[x])-30[x]}
a}

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A lambda returning an array of strings.

My initial impulse was to generate the columns and transpose them, but it's much easier to just avoid that step.

I would have liked to initialize a with [" "*30]*5, but that would make shallow copies of the strings, resulting in a very fat, non-slithery snake.

I could have used a constant like D as the increment (for the same byte count), but Ruby would have complained every time I assigned it. I decided I prefer decreasing readability by reusing i mid-loop to having a bunch of Debug warnings to ignore.

I also would have liked to save a few bytes with loop{x+=rand(3)-1;(0..4)===x&&break}, but that would have caused a bias on the edges: 1/3 chance to turn back inward, 1/3 chance to stay, and 1/3 chance to go out of bounds for a while before eventually random-walking back in (that is, "stay").

-20 bytes: Use Ruby's Integer#[] to create tiny conditionals, ensuring correct movement weightings for all 5 positions. This replaces a loop-break pattern (with a nonzero chance of failing to halt) for a huge savings. Thanks, Eric Duminil!

-1 byte: Initialize a with (0..4).map instead of 5.times, thanks again to Eric Duminil.

->{
  a = (0..4).map{ " " * 30 }      # a is the return array: 5 strings of 30 spaces
  x = 2                           # x is the snake position
  30.times{ |i|                   # For i from 0 to 29
    a[x][i] = ?@                  #   The ith position of the xth row is modified
    x += rand(3 - 17[x]) - 30[x]  #   Using bit logic, add rand(2 or 3) - (0 or 1)
  }
  a                               # Return the array of strings
}

Answer 20

Python 3, 123 bytes

from random import*
i,*a=2,
exec("a+=i,;i+=randint(-(i>0),i<4);"*30)
for x in range(5):print(''.join(' 0'[x==i]for i in a))

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Generate an array of integers, then convert it to each row.

Python 2, 120 bytes

from random import*
i=2;a=[]
exec"a+=i,;i+=randint(-(i>0),i<4);"*30
for x in range(5):print''.join(' 0'[x==i]for i in a)

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For Py2, redundant parens for exec and print can be removed, but the syntax in the 2nd line is invalid.

Outgolfing both Py2 submission by Rod and Py3 submission by linemade.

Answer 21

Perl 6, 85 bytes

.join.say for [Z] ((' ',' ',0,' ',' '),{.rotate(set(0,+?.[0],-?.[4]).pick)}...*)[^30]

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The long parenthesized expression is a lazy sequence generated from the initial element (' ', ' ', 0, ' ', ' '), the first vertical strip of the output. Each successive strip/list is generated from the preceding one by calling its rotate method, with the offset randomly chosen from a set containing 0, 1 (if the first element is nonzero), and -1 (if the fifth element is nonzero).

The matrix of horizontal strips is transposed with the [Z] operator, turning it into a list of vertical strips, each of which is then joined into a single string and output with say.

Answer 22

PowerShell, 133 bytes

$a=(,' '*30),(,' '*30),(,' '*30),(,' '*30),(,' '*30);$l=2;0..29|%{$a[$l][$_]=0;$l+=0,(1,($x=1,-1),$x,$x,-1)[$l]|Random};$a|%{-join$_}

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Constructs a 2D array of 30 spaces wide by 5 lines tall. (NB - if someone can come up with a better effective way to initialize this array, I'll <3 you forever.) Sets helper variable $l to 2 (this is used for what line the previous snake segment was on). Then loops from 0 to 29.

Each iteration, we set our snake element to 0. Then we index into a complicated array with Get-Random that selects out whether we go up or down or stay the same. That's added back into $l.

Finally, we loop through the five elements of $a and -join their inner elements into a single string each. Those five strings are left on the pipeline, and the implicit Write-Output gives us newlines for free.

Answer 23

Clojure, 123 bytes

Here come the parens:

(let[l(take 30(iterate #(max(min(+(-(rand-int 3)1)%)4)0)3))](doseq[y(range 5)](doseq[x l](print(if(= y x)0" ")))(println)))

Ungolfed version:

(let [l (take
       30
       (iterate
        #(max
          (min
           (+ (- (rand-int 3) 1) %)
           4)
          0)
        3))]
(doseq [y (range 5)]
  (doseq [x l]
    (print (if (= y x) 0 " ")))
  (println)))

Builds a list of the different heights of the snake body, then iterates from 0 to 4. Whenever a height matches the current row it prints a 0, otherwise a blank. Not letting the heights exceed the boundary really costs bytes. Also recognizing when a new line is in order is more byte-intensive as it should be. One could easily write a single doseq, making a cartesian product of the x's and y's but then one does not know when to print a new line.

Answer 24

Python3 +numpy, 137 132 bytes

Not the shortest python submission, not the longest, and definitely not the fastest.

from pylab import*
j=r_[2,:29]
while any(abs(diff(j))>1):j[1:]=randint(0,5,29)
for i in r_[:5]:print(''.join(' #'[c] for c in j==i))

update Using numpy's diff command saved 5 bytes for testing if the snake is a valid pattern, compared to calculating the difference manually with j[1:]-j[:-1].

Answer 25

C (gcc), 80 76 72 71 bytes

a[5][30],i,r;f(){for(r=2;i<30;r+=rand()%3-1)a[r=r>4?4:r<0?0:r][i++]=1;}

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Answer 26

R, 95 bytes

x=3;l=1:5
write(t(replicate(30,{y=ifelse(x-l,' ',0);x<<-sample(l[abs(x-l)<2],1);y})),'',30,,'')

Next line x is always chosen from lines that are no more than 1 away from current line (l[abs(x-l)<2]). Using replicate instead of a for cycle saves some bytes needed for matrix initialization and manipulation and requires the use of the <<- operator when assigning to the global variable x.

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Answer 27

05AB1E, 25 bytes

Y30F©ð5×0®ǝs<DÌŸ4ÝÃΩ}\)ζ»

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Explanation

Y                           # push the initial value 2
 30F                        # 30 times do
    ©                       # store a copy of the current value in register
     ð5×                    # push 5 spaces: "     "
        0®ǝ                 # insert 0 at the position of the current value
           s<DÌŸ            # push the range [current-1 ... current-1+2]
                4ÝÃ         # keep only numbers in [0 ... 4]
                    Ω       # pick one at random
                     }\     # end loop and discard the final value
                       )ζ   # transpose the list
                         »  # join by newlines