Draw my downslashes

Question

As a programmer, you've probably heard of forward slashes and backward slashes. But have you heard of downslashes? That's when you take a bunch of slashes, connect their ends and draw them going down.

For today's challenge, you must write a program or function that takes a string consisting purely of slashes, and outputs all of those slashes drawn downwards in a line connecting them. This will be a lot more clear if you see an example. Given the string \\\//\/\\, you should output:

\
 \
  \
  /
 /
 \
 /
 \
  \

Here are some clarifications:

• There must be one slash per line.

• The first line will have 0 leading spaces.

• For each pair of slashes:

  • If they are different from each other, they will be drawn in the same column. For example, \/ will give:

    \
    /
    

  • If they are the same character, the lower one is in the direction pointed to, that is moving to the right for a backslash, and moving to the left for a forward slash. So \\// will give

    \
     \
     /
    /
    

• Each line may have extra trailing whitespace as long as this doesn't change the visual appearance of the output. Up to one trailing and leading newline is also acceptable. Extra leading spaces are not permitted!

In order to keep this simpler, you can assume that the string will never contain too many forward slashes. In other words, no prefix of the input will contain more forward slashes than backslashes, so an input like \\//// or // will never be given. This also means that every input will start with a backslash.

If your input is taken as a string literal, you may escape the backslashes if this is necessary. You will also never need to handle an input that is empty, or contains characters other than a slash.

You may output by any reasonable format.

As usual, this is a code-golf challenge, so try to make the shortest solution possible, even if you pick a language where this is rather difficult. Bonus points for explaining any interesting techniques you used to take bytes off!

Examples

#Input
\\\\\\\\\\\

#Output
\
 \
  \
   \
    \
     \
      \
       \
        \
         \
          \

#Input
\\\//\\/\//\\///

#Output
\
 \
  \
  /
 /
 \
  \
  /
  \
  /
 /
 \
  \
  /
 /
/


#Input
\/\/\/

#Output
\
/
\
/
\
/

Answer 1

Perl, 40 + 2 bytes

/\//&&$.--,say($"x$.,$_),/\\/&&$.++for@F

You need the -F flag.

Answer 2

V, 14 bytes

\/j>G
ç¯/<G

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Answer 3

Perl, 34 38 + 1 bytes

to handle the two cases

s,(/)|.,$"x($1?$c&&--$c:$c++).$&.$/,ge

to be run with -p option

s,(/)|.,$"x($1?--$c:$c++).$&.$/,ge

EDIT: following comment doesn't work when first character is /

s,(/)|.,$"x($1?$c--:++$c).$&.$/,ge

however output will be shifted one character on the right if first char is \

Answer 4

VBA (Excel), 181 bytes

Sub q()
a = Cells(1, 1)
For x = 1 To Len(a)
c = Mid(a, x, 1)
If c = "\" Then: Debug.Print b & c: b = b + " "
If c = "/" Then: b = Left(b, Len(b) - 1): Debug.Print b & c
Next
End Sub

Answer 5

Pyth, 24 21 bytes

Port from Rod's answer.

VQ=-Z<N\<+*ZdN=+Z>N\<

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Answer 6

SOGL V0.12, 16 13 bytes

{└=-:↕PFoF┘=+

Try it Here! - expects input on the stack, so for ease-of-use , is added

Answer 7

Excel VBA, ₇₄ 72 Bytes

Anonymous VBE immediate window function that takes input from cell [A1] and outputs to the VBE immediate window

For i=1To[Len(A1)]:c=Mid([A1],i,1):s=s+(c="/"):?Spc(s)c:s=s-(c="\"):Next

Example I/O

[A1]="\\\//\\/\//\\///"
For i=1To[Len(A1)]:c=Mid([A1],i,1):s=s+(c="/"):?Space(s)c:s=s-(c="\"):Next
\
 \
  \
  /
 /
 \
  \
  /
  \
  /
 /
 \
  \
  /
 /
/

Answer 8

Implicit, 25 bytes

~.(´?`/ò](0ß´);@ß1?`\ó~.ö

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Ungolfed/explanation:

~.         read input, increment
(          do..while top of stack truthy
 ´         decrement

 ?`/{      if input equal to /
   ]´[      decrement memory
 }

 ](0       pull memory, do..while truthy
  @32       print a space
  ´         decrement
 );        pop

 @@10      print input, print a newline

 ?`\{      if input equal to \
   ].[      increment memory
 }

 ~.        read input, increment
)          loop
&          exit (avoid implicit output)

Note that ß is equal to @32, ò is equal to ]´[, ó is equal to ].[, and ö can be used in place of )& when at the end of a program.

Answer 9

Python 3, 78 bytes

a,x='',0
for i in input():x+=((1*i!='/')-(1*i=='/'))*(a==i);print(' '*x+i);a=i

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Answer 10

brainfuck, 151 bytes

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

Try it online!

Answer 11

J, ^{28 27} 22 bytes

({."0~+/\-0&<)_1^'\'=]

Try it online!

Thanks to Bubbler for catching a bug and for -6 bytes!

Answer 12

C (gcc), 96 71 70 bytes

Awesome -25 solution by ceilingcat

And another -1 by ceilingcat. ASCII bit hacks ftw

c;p;main(i){for(;read(0,&c,1);printf("%*c\n",i,p=c))c-p?:c&1?--i:++i;}

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Ungolfed

c; /* character */
p; /* previous character */

main(i /* indent */)
{
    for (; read(0, &c, 1); printf("%*c\n", i, p = c))
        c - p ? : c & 1 ? --i : ++i;
}

Explanation

read takes 1 byte from the file descriptor 0 (stdin) and stores it in c.

c - p checks if c and p are different. c & 1 checks if c is a forward slash. So the entire conditional increments the indent if the character and the previous character are both backslashes, and decrements the indent if they're both forward slashes.

Then we print c with i leading spaces. We also assign p = c for the next iteration.

Answer 13

PowerShell, 47 bytes

switch($args){'\'{' '*$i+++$_}'/'{' '*--$i+$_}}

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Answer 14

PowerShell, 71 69 bytes

^{-2 bytes thanks to mazzy}

$z=92
$args|%{$i+=($x=2*($_-eq92)-1)*($z-ne$_)
' '*$i+($z=$_)
$i+=$x}

Try it online!

Takes input by splatting. This also saves us two bytes because we can just treat it as an int instead of writing '\' which we do twice.

Answer 15

Excel, 125 bytes

=LET(q,SEQUENCE(LEN(A1)),x,MID(A1,q,1),REPT(" ",MMULT(IF(TRANSPOSE(q)>q,,1),IF(q=1,,(INDEX(x,q-1)="\")-(INDEX(x,q)="/"))))&x)

Link to Spreadsheet

This is a port of Taylor Scott's VBA answer.

Explanation

• =LET(q,SEQUENCE(LEN(A1)), q = vertical array [1..LEN(A1)]
• x,MID(A1,q,1), x = The characters in A1 in a vertical array
• IF(q=1,,(INDEX(x,q-1)="\")-(INDEX(x,q)="/")) the change in the number of spaces from the prior line; +1 if the prior line was "", -1 if the current line is "/"
• IF(TRANSPOSE(q)>q,,1) a lower triangular matrix of 1s
• MMULT(~,~) matrix multiply the change array and the lower triangular matrix to get the number of spaces for each line
• REPT(" ",~)&x) for each line output the number of spaces & characters

Answer 16

Pyth, 20 bytes

jm?qd\\+*;~hZd+*;=tZ

Test suite

The other two existing Pyth answers use different approaches (and an older version of the language).

Explanation:

jm?qd\\+*;~hZd+*;=tZ   | Full program
jm?qd\\+*;~hZd+*;=tZdQ | with implicit variables added
-----------------------+------------------------------------------------
 m                   Q | For each character d in the input:,
  ?qd\\                |  if d is '\',
        *;             |   create a string of n spaces, where n is
          ~hZ          |    Z, but then store Z + 1 in Z (Z begins as 0)
       +     d         |   add d to the end of the string
  ?                    |  otherwise,
              +*;   d  |   do the same, but with (below) spaces
                 =tZ   |    Z - 1, stored in Z
j                      | Join the results by newline.

Answer 17

Vyxal, 8 bytes

Cæ:d⌐¦+↳

Try it Online! Outputs as a list of lines, formatting in footer

C        # Charcodes: "/" -> 47, "\" -> 92
 æ       # Are prime? "/" -> 1, "\" -> 0
   d⌐    # Double and take one's complement "/" -> -1, "\" -> 1
     ¦   # Cumulative sums
      +  # Add...
 æ:      # Is prime? (indents "/" by one extra space)
       ↳ # Pad to these lengths

Answer 18

Julia 1.0, 67 bytes

s->(x=[s...];@.println(lpad(x,$cumsum(1-2(x<'0')-[0;$diff(x)]%2))))

Try it online!

• -3 bytes thanks to @MarcMush: replace isodd(_) with (_.%2)
• -6 bytes thanks to @MarcMush: use @. to vectorize multiple expressions
• -3 bytes thanks to @amelies: replace string repeats with lpad
• -1 byte thanks to @MarcMush: replace 'x=='/' with x<'0'

Answer 19

Rockstar, 110 92 90 bytes

listen to S
cut S
Y's -1
while S
roll S in C
let Y be+C's "\"
say " "*Y+C
let Y be-C's "/"

Try it here (Code will need to be pasted in)

listen to S     :Read input string into variable S
cut S           :Split into an array
Y's -1          :Initialise Y as -1
while S         :While S is not empty
roll S in C     :  Pop the first element into variable C
let Y be+       :  Increment Y by
  C's "\"       :    C is equal to "\"
say " "*Y+C     :  Output Y spaces & C
let Y be-       :  Decrement Y by
  C's "/"       :    C is equal to "/"

Answer 20

Thunno 2, 11 bytes

JCPDḌ€ḷṡ+ðṙ

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Explanation

JCPDḌ€ḷṡ+ðṙ  # Implicit input
JC           # Charcodes of input
  PD         # Are prime, duplicate
    Ḍ€ḷ      # Double, complement
       ṡ+    # Add to cumsums
         ðṙ  # Right-justify
             # Implicit output

Answer 21

Python 2, 86 76 75 bytes

-1 byte thanks to Neil.

p,i='',0
for c in input():i+={'\\\\':1,'//':-1}.get(p+c,0);print' '*i+c;p=c

Try it online!

Fairly lame approach, I will try to golf the mapping at least. NVM I got rekt by another answer. >_>

Answer 22

Rust, 165 bytes

fn f(s:&str){let(_,a)=s.chars().fold((0,"".to_string()),|(i,r),c|(if c<'<'{i-1}else{i+1},format!("{}{}{}\n",r," ".repeat(if c<'<'{i-1}else{i}),c)));println!("{}",a)}

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It's an adaptation of Rod's answer in Python 2.

Answer 23

c64 basic v2, 71 70 61 bytes

1rEs:x=1024:fOy=1tolE(s):a=aS(mI(s,y,1)):pOx,a:x=x-165+a*2:nE

Input can be given as

0dA"\\/\/\\/\//"

If the string is longer as 25, the program will overwrite its own memory. And we won't do that, because basic programs overwriting themselves with POKEs contradict the OO paradigm.

Answer 24

GolfScript - 117 bytes

1/{'/'=}%1:s;[{s}{..(\;!?.0<{;,0:s;}{.@\>}if}while]0:M;1:i;{,{i*}%:a{M+' '*i 0<{'/'}{"\\"}if +"\n"+}/a)M+:M;;i~):i;}/

Ungolfed version

1/{'/'=}%
1:s;
[{s}
{
  ..(\;!?.0<{;,0:s;}{.@\>}if
}
while]
0:M;
1:i;
{
  ,{i*}%:a{M+' '*i 0<{'/'}{"\\"}if +"\n"+}/
  a)M+:M;;
  i~):i;
}/

At first glance it looked easy... it took me 2.5 hours. Probably there is room for improvement, perhaps tomorrow I'll do some optimization.

Answer 25

SmileBASIC, 65 bytes

INPUT S$WHILE""<S$C$=SHIFT(S$)DEC N,@L>C$?" "*N;C$INC N,@H<C$WEND

Answer 26

JavaScript, 49 48 bytes

Takes input as an array of individual characters and outputs an array of lines.

a=>a.map(c=>" ".repeat(x+=d=c>'/',x-=!d)+c,x=-1)

Saved a byte borrowing a trick from the other JS solution.

---

Try it

f=
a=>a.map(c=>" ".repeat(x+=d=c>'/',x-=!d)+c,x=-1)
o.innerText=[String.raw`\\\\\\\\\\\\`,String.raw`\\\//\\/\//\\///`,String.raw`\/\/\/`].map(s=>f([...s]).join`\n`).join`\n\n`
oninput=_=>o.innerText=f([...i.value]).join`\n`

<input id=i><pre id=o>

Answer 27

K4, 31 bytes

Solution:

-1(-1+\a-a*~~':a:-1 1"/"=x)$$x:

Examples:

q)k)-1(-1+\a-a*~~':a:-1 1"/"=x)$$x:"\\\\\\//\\\\/\\//\\\\///"
\
 \
  \
  /
 /
 \
  \
  /
  \
  /
 /
 \
  \
  /
 /
/

Works if you start with a / too:

q)k)-1(-1+\a-a*~~':a:-1 1"/"=x)$$x:"/\\\\/\\\\/"
/
\
 \
 /
 \
  \
  /

Explanation:

Generate list of negative numbers to (left) pad each of the input characters. Struggled to get a formula that worked, will look at the other solutions to see if there is a more simple method:

q)k)"/"=x
0001100101100111b
q)k)-1 1"/"=x
-1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 1
q)k)~~':a:-1 1"/"=x
1001010111010100b
q)k)a*~~':a:-1 1"/"=x
-1 0 0 1 0 -1 0 1 -1 1 0 -1 0 1 0 0
q)k)a-a*~~':a:-1 1"/"=x
0 -1 -1 0 1 0 -1 0 0 0 1 0 -1 0 1 1
q)k)+\a-a*~~':a:-1 1"/"=x
0 -1 -2 -2 -1 -1 -2 -2 -2 -2 -1 -1 -2 -2 -1 0
q)k)-1+\a-a*~~':a:-1 1"/"=x
-1 -2 -3 -3 -2 -2 -3 -3 -3 -3 -2 -2 -3 -3 -2 -1

Full breakdown:

-1(-1+\a-a*~~':a:-1 1"/"=x)$$x: / the solution
                             x: / save input as variable x
                            $   / string (converts to char lists))
                           $    / pad
  (                       )     / do this together
                     "/"=x      / boolean list of x equal to /
                 -1 1           / index into this list
               a:               / save as variable a
           ~~':                 / differ (not-not-each-previous)
         a*                     / multiply by a
       a-                       / subtract from a
     +\                         / sums
   -1                           / (start summing from -1)
-1                              / print to stdout

Answer 28

Japt -R, 13 bytes

¬®ùZ>'/?°V:V´

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Unpacked & How it works

Uq mZ{ZùZ>'/?++V:V--

Input: U = string of / and \, V = 0 (default)

Uq                    Split into chars
   mZ{                Map...
        Z>'/?           If the char is rightward (backslash)...
             ++V          Pre-increment V
                :V--      Otherwise, post-decrement V
      Zù                Left-pad the char with spaces to length V

-R                    Join with newline before printing

Answer 29

Pip, 28 bytes

FlaIlQ'\PsX++v.lE{PsXv.l--v}

With a post decrement operator, this could be way shorter.

Try it online!

Answer 30

Ruby, 47 42 bytes

-5 bytes thanks to Steffan

Inspired by pxeger's Zsh answer.

->a{w=0
a.map{" "*(_1<?@?w-=1:~-w+=1)+_1}}

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