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I have an ASCII-art box and I need a program to open it.



|     |


|     |


  • The first line will only consist of -, at least 3 of them
  • The middle rows will start with | have spaces, and end with |
    • All the middle rows will be the same
  • The last row will start with | have _ and end with a |
  • All rows will be the same length

Opening the box:

  • Each - should be replaced by a / in ascending lines and position.
share|improve this question
As opposed to the game "Shut the Box"? – VTCAKAVSMoACE Jan 31 at 19:14
cough – VTCAKAVSMoACE Jan 31 at 21:24
The lid becomes twice as long when opened? Oh well, blame ASCII art. – Darrel Hoffman Jan 31 at 21:46
What's in the box? – Williham Totland Feb 1 at 11:58
There's not a working interpreter, so I guess not then. Doesn't matter; when I do make the interpreter (soon, hopefully), I'll post the answer. – ETHproductions Feb 1 at 16:10

24 Answers 24

up vote 6 down vote accepted

CJam, 14 bytes


Try it online!

How it works

l               Read the first line from STDIN.
 ,              Compute the line's length. Result: L
  {      }%     Map; for each I in [0 ... L-1]:
                  (implicit) Push I.
   N              Push a linefeed.
    '/            Push a slash.
      @           Rotate I on top of the stack.
       S*         Turn I into a string of I spaces.
           W%   Reverse the resulting array of strings and characters.
             q  Read the remaining input from STDIN.
share|improve this answer

JavaScript ES6, 57 bytes

$'/`))[r](/-/g,' ')

Outputs a leading newline. Works by taking the row of -s and converting them into a triangle, then replacing the -s with spaces.

Edit: Saved 5 bytes thanks to @edc65.

share|improve this answer
+1 I learned something new ($'). Instead this old trick can save 4 bytes for you: f=s=>s[R='replace'](/-+/,s=>s[R](/-/g,"\n$'/"))[R](/-/g,' ') – edc65 Jan 31 at 21:01
@edc65 Thanks, I actually make it 5 bytes; also thanks for fixing my typo (as you might have guessed I develop with \n and convert afterwards). – Neil Jan 31 at 22:42

Pyth, 16 14 bytes



   m      Uz   - [V for d in range(len(input()))]
    +*;d\/     - " "*d + "/"
  _            - ^[::-1]
j+          .z - "\n".join(^+rest_of_input())

Thanks @FryAmTheEggman for new algorithm!

Try it here.

share|improve this answer

pb (NONCOMPETING), 125 bytes


The version of pbi that you need to run this answer is newer than the question. It would have worked in older versions except that I never got around to allowing newlines in input. Oh well.

First, this determines the height of the box by counting newlines in the input. Once it knows that, it goes to the Y location of the right side of the box, goes down to where it needs to be and draws the walls and floor, finishing with the lid.

Check out this fun animation!

The long pause is the brush going over the input.


^w[B!0]{>}                # Go to the end of the input
w[B!45]{<                 # Head left until hitting a hyphen
    w[B=10]{                # For each newline on the way:
            t[T+1]                # Count it
            b[0]                  # Delete it

v[X]                      # Move down as far as it is right + the number of \n
v                         # one

w[T!0]{                   # While the counting variable is nonzero:
    vb[124]                 # Go down and draw a pipe
    <[X]b[124]              # Draw a pipe on the left as well
    >w[B=0]{>}              # Go back to the right side
    t[T-1]                  # Decrement variable

w[X!1]{<b[95]}            # Draw the bottom of the box
<w[B!0]{^}                # Go up the left wall
w[Y!-1]{b[47]>^}          # Go up and right, drawing the lid
share|improve this answer
+1 for the cool animation. How did you create it? – Gowtham Feb 1 at 18:49
@Gowtham I would guess you record your screen and crop the video. Then, take that and convert it to a GIF. Of course, just guessing, I don't know the actual method – Spotlight Feb 2 at 3:42
@awesomebing1 you got it – undergroundmonorail Feb 2 at 11:47

Retina, 34 20 bytes


In the first step every - is substituted with the -'s following it, a / and a newline. The newline at the end of the original first line is deleted. In the second step we change the new -'s to spaces which results in the desired output.

Try it online here.

share|improve this answer
Just for the fun of it, it's also possible in a single stage:… (same bytes though) – Martin Ender Feb 2 at 12:33

MATL, 14 15 bytes

' /'jnXyPQ)`jt

Input should have a trailing newline.

Try it online!


' /'       % push string (will be indexed into to generate the open lid)
jn         % read first line of input and push its length
Xy         % identity matrix with that size
P          % flip vertically
Q          % add 1. Now the matrix contains 1 and 2, to be used as indices
)          % index into string. Produces a 2D char array for the lid
`          % do-while loop
  j        %   push input line
  t        %   duplicate. Truthy if nonempty
           % implicitly end loop. The loop condition is the top of the stack,
           % that is, the input line that has just been read.
           % This is truthy if non-empty; and in that case another line will
           % be read in the next iteration.
           % implicitly display stack contents, bottom to top
share|improve this answer

JavaScript (ES6), 66

`+t,l+=' '),l=''),t)


f=b=>([a,t]=b.split`-\n`,[...a+0].map(_=>(t=l+`/\n`+t,l+=' '),l=''),t)

var box = `-------
|     |


<pre id=O></pre>

share|improve this answer

Japt, 28 26 25 22 18 17 bytes

{SpUa- -Y}/

Test it online!

Outputs a leading newline, which is acceptable according to the OP.

How it works

Ur-@       // Replace each hyphen X in the input and its index Y with this function:
"          //  Start a string that contains a newline.
{        } //  Insert here:  
   Ua- -Y  //   Take the index of the last hyphen in the input, subtract Y,
 Sp        //   and return that many spaces.
/          //  Finish off the string with a slash.

This would be 4 bytes shorter if the hinge is allowed to be on the right edge of the box:

share|improve this answer

Python 3, 1̶7̶0̶ 88 bytes

Here is my short(er) code: EDIT: Now 82 bytes Shorter With @Dennis 's Code Edit!

while d:d-=1;print(' '*d+'/')

Python 3, 421 bytes

Alternatively, just for fun, you could use one that opens it slowly:

import time
import os
f = open('f.txt', 'r')
e = f.readline()
a =
d = len(e)
c = 0
t = e + a
g = ''
clear = lambda: os.system('cls')
while c <= d - 1:
    print(("\n" * ((d - 1) - (c))) + t)
    c += 1
    e1 = e[0:(d - c)  -1]
    e2 = e[(d - c):len(e)]
    e1 += '/'
    e2 = ' ' * len(e2)
    y = (' ' * len(e1)) + '/' + '\n'
    g += y
    t = (g + e1 + e2 + '\n' + a)[d:len(g + e1 + e2 + '\n' + a)]

To use either, you must create a text file in the same directory containing an ascii box of any width or depth called 'f.txt'. It will then open that box.

share|improve this answer
You can shorten this further by shortening variables to single letters and removing a lot of the whitespace between operators. For general tips for golfing in Python, see here. – Alex A. Jan 31 at 23:08
Why on earth do you need time? This question only asks for a single output. – VTCAKAVSMoACE Jan 31 at 23:19
Like I said, my interpretation of this puzzle was slightly off and if you output it it'll show you more than the question asked for. – Monster Jan 31 at 23:21
Okay, I have added a simplER answer which does exactly what the question says as I now understand it. It's not pretty but it works. My alternate code is for anyone awesome enough to want to watch it open – Monster Jan 31 at 23:59
A few minor changes bring your byte count down to 81 (reading from STDIN). – Dennis Feb 1 at 1:01

Perl, 61 54 33 + 3 = 36 characters

s^-^" "x(length$')."/\n"^ge&chomp

Run it as

perl -ple 's^-^" "x(length${chr 39})."/\n"^ge&chomp' closed_box_file

Each - in first line is replaced by a string that is a result of concatenation of some number of , / and \n. ${chr 39} evaluates to perl's (in)famous $' aka $POSTMATCH special variable. Lastly, chomp gets rid of the trailing newline character that was added for the last - character.

Thanks to @manatwork for saving 7 + more characters.

Bonus - s^-^" "x$i++."\\\n"^ge&&chop opens the box from the right edge in 29 + 3 characters :). Run it as:

gowtham@ubuntu:~$ cat a
|  |
gowtham@ubuntu:~$ perl -plE 's^-^" "x$i++."\\\n"^ge&&chop' closed_box_file
|  |
share|improve this answer
@manatwork Only first line contains -, so yes, I can golf it even more. Thanks! – Gowtham Feb 1 at 19:12
$.==1$.<2, &&chop&chop, remove the extra pair of parenthesis around length, count {chr 39} as 1, as it not is only needed by the command line version due to shell's syntax: $.<2&&s^-^" "x(length$')."/\n"^ge&chop + 2 character for command line options = 40 according to my counting. – manatwork Feb 1 at 19:17
@manatwork Actually, $.==1 or $.<2 can be eliminated because only first line contains - – Gowtham Feb 2 at 6:54
Yes, I saw what you did there. And I was amazed. By the way, you can use a literal line wrap in the code instead of \n. – manatwork Feb 2 at 8:53
Doh. Found a shorter one: s^-^$'=~y/-/ /r."/\n"^ge&chomp – manatwork Feb 3 at 19:05

Pyth, 26 23 bytes

jXK.z0jm+*\ t-lhKd\/lhK

Yuck. Can definitely be shorter; still working on it.

share|improve this answer

Java 8, 158 118 bytes

This is just a start, but hey, FGITWFTW.

n->{String o="";int z=n.lastIndexOf("-"),i=z;for(;i-->0;o+="/\n")for(int y=i;y-->0;o+=" ");return o+n.substring(z+2);}

Expects input as a string, returns the box.

share|improve this answer

Python3, 76 bytes

while w:w-=1;print(' '*w+'/')
  1. Get the length of the first input line.
  2. Print lines of / preceded by a decreasing number of spaces.
  3. Push the rest of stdin straight to stdout.

EDIT: I've just noticed that my code is almost identical to @Dennis' comment edit of @Monster's shorter Python3 code, the only difference being print the remainder of stdin directly instead of store it in a variable. Great minds!

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Bash, 85 84 79 characters

(Pure Bash version, no external commands used.)

[[ $a = -* ]]&&r
mapfile a
echo "${a[*]}"

Outputs a leading newline.

Sample run:

bash-4.3$ bash <<< $'-------\n|     |\n|_____|'

|     |
share|improve this answer
echo is an external command - /usr/bin/echo ;) – Levi Feb 3 at 1:12
The echo executable exists for the operating system's conformance with the standards. Nowadays that one is only used if portability is important, as that one is up to the standard, But most modern shells have their own builtin echo which is used by default: @Levi, if you rename/move your /usr/bin/echo, my code will still work. – manatwork Feb 3 at 9:25
(it was a joke....) – Levi Feb 4 at 5:31
Oh. Ok. Sorry, I already met people earlier who claimed the same, but seriously. – manatwork Feb 4 at 8:43

Python 2, 100 bytes

def o(b):
 print"\n".join(["/".rjust(i)for i in range(len(m[0]),0,-1)]+m)

Defines a function o that takes a string as its input. (Full program wasn't specified in the question).

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JavaScript ES6, 106 bytes

`,n=q[0].length,eval('for(i=0,r="";i<n;i++)r+=" ".repeat(n-i-1)+"/\\n"'),r+q.slice(1).join`

Simple enough: getting the length of the first line, creating a spaced-triangle with trailing /, and adding that to the original, sliced and joined.

Test it out! (ES6 only :()

`,n=q[0].length,eval('for(i=0,r="";i<n;i++)r+=" ".repeat(n-i-1)+"/\\n"'),r+q.slice(1).join`
function n(){q.innerHTML=F(o.value)}
<textarea id=o>----
|  |
|__|</textarea><div id=q>

share|improve this answer
I see you solved the XKCD problem using formatting. Clever. – Kroltan Feb 2 at 12:10

Python 2.7, 120 122 chars

Needs a file f with the original/closed box, output is the opened one. Cheers to @Monster for the idea... will try to figure out multi-line input later and see if it's shorter.

for l in open('f').readlines():
 if l[1]==('-'):
  for x in range(1,len(l)):print(' '*(len(l)-x+1)+'/')
 else:print l[:-1]


  • just noticed that the leftmost / has a space in front; +2 bytes
share|improve this answer

Ruby, 59 characters

(57 characters code + 2 characters command line options.)

$_=${(s<<" ")[1..-1]+?/}.reverse*$/if$.<2

Sample run:

bash-4.3$ ruby -ple 's="";$_=${(s<<" ")[1..-1]+?/}.reverse*$/if$.<2' <<< $'-------\n|     |\n|_____|'
|     |
share|improve this answer

Bash, 129 characters

Requires a file called a with the closed box, outputs to stdout.

for i in $(seq `cat a|awk 'NR==1{print length($1)-1}'` -1 1);{ for j in `seq 1 $i`;{ printf " ";};echo "/";};echo "/";tail -n2 a

It might be possible to make it shorter by using sed and using stdin and piping.

share|improve this answer
Nice first golf answer. Some simple syntax change suggestions: for i in $(seq `awk 'NR<2&&$0=length-1' a` -1 1);{ for j in `seq 1 $i`;{ printf \ ;};echo /;};echo /;tail -n2 a – manatwork Feb 1 at 15:13

PowerShell, 55 bytes

$d,$b=$args-split"`n";($d.length-1)..0|%{" "*$_+"/"};$b

Takes input $args as a string, -splits on newlines `n (reference link), stores the first line into $d (as a string) and the remaining into $b (as an array of strings). We then loop from the length of the first line (minus 1) to 0 and each iteration output that number of spaces plus a /. Finally, output $b (the rest of the input string) which by default will output one per line.

Example Run

PS C:\Tools\Scripts\golfing> .\help-me-open-the-box.ps1 "----`n|  |`n|__|"
|  |
share|improve this answer

PHP, 127 characters

$s=$argv[1];$l=strlen(strtok($s,"\n"));for($i=0;$i<$l;$i++)$s=preg_replace("/-/","\n".str_repeat(" ",$l-$i-1)."/",$s,1);echo$s;

Ungolfed version :


    $v="\n".str_repeat(" ",$l-$i-1)."/";
echo $s;
share|improve this answer
There is a typo in your code: you missed the sigil of $argv. There are a couple of minor tricks you could apply: $l=strlen(strtok($s=$argv[1],"↵"));while($l)$s=preg_replace("/-/","↵".str_repea‌​t(" ",--$l-$i)."/",$s,1);echo$s; (Use a literal newline in your code where is “↵”: ) – manatwork Feb 1 at 17:03

Python, 125 bytes (110 without box)

i="\n---\n| |\n|_|"
for x in r(1,l):print" "*(l-x)+"/"
for x in r(2,len(b)):print b[x]

If anyone has any idea how to shorten it, please let me know!

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Awk, 47 46 characters

(44 characters code + 2 characters command line option.)

/-/{OFS=RS;for(i=NF;i;i--){$i=s"/";s=s" "}}1

Sample run:

bash-4.3$ awk -F '' '/-/{OFS=RS;for(i=NF;i;i--){$i=s"/";s=s" "}}1' <<< $'-------\n|     |\n|_____|'
|     |
share|improve this answer

Gema, 51 49 31 characters

-\P/-+/=@subst{-=\\ ;$1}/\n

Sample run:

bash-4.3$ gema -e '-\P/-+/=@subst{-=\\ ;$1}/\n;-=/' <<< $'-------\n|     |\n|_____|'
|     |
share|improve this answer

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