The Great Pyramid of ASCII

Question

Introduction

It's 2600 BC and people are building pyramids now. They already made the basis of the pyramid but don't know how to continue. So, they called you for help.

The rules of making a pyramid is quite simple. For the layer above the previous layer, all you need to do is follow this step-by-step hand guide:

Cut the edges off the previous layer.
Above the / character, there must be a \ character and vice versa. This applies to every character except the edges.
The leftmost character is always a / and the rightmost character is always \.

Let's take an example of a basis for a pyramid:

//\/\/\\

We cut off the edges, leaving:

 /\/\/\

We change the forward slashes with backward slashes and vice versa:

 \/\/\/

The leftmost character is always a / and the rightmost character is always a \, so we change that:

 //\/\\

We place this layer on the previous layer:

 //\/\\
//\/\/\\

We continue until the top is reached (which looks like /\). So, eventually we get:

   /\
  //\\
 //\/\\
//\/\/\\

This is what you need to output.

The task

Given the basis of a pyramid (with a length greater than 3), output the full pyramid. You can safely assume that the leftmost character is / and the rightmost character is a \. You can also assume that the length of the basis is always even. The use of trailing spaces is allowed. The use of leading spaces is also allowed, as long as the pyramid stays in place. The use of 1 trailing and 1 leading newlines is allowed.

Test cases

Input: /\\\
Output:
 /\
/\\\

Input: //\\///\/\
Output:
    /\
   /\\\
  /\///\
 ///\\\/\
//\\///\/\

Input: /////////////\
Output:
      /\
     /\\\
    /////\
   /\\\\\\\
  /////////\
 /\\\\\\\\\\\ 
/////////////\

This is code-golf, so the submission with the least amount of bytes wins!

@LeakyNun They are allowed, I'll edit that in. – Adnan yesterday — Adnan, yesterday

Leaky Nun · Answer 1 · 2016-08-20 19:08:33Z

up vote 11 down vote

Retina, 59 56 54 52 bytes

{`^( *)/.(.*)..
$1 /$2\¶$0
T`/\\`Ro`(?<=^ +/).+(?=.)

Try it online!

Sample output

    /\
   /\\\
  /\///\
 ///\\\/\
//\\///\/\

edited yesterday

answered yesterday

Leaky Nun

14.2k235115

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Maltysen · Answer 2 · 2016-08-20 22:35:49Z

up vote 10 down vote

Pyth - 27 26 bytes

Reduces by the operation given in the OP until it repeats, which is the case for the blank line.

j_.e+*kdb.ujXtPtPNK"\/")_K

Test Suite.

edited yesterday

answered yesterday

Maltysen

14.5k13385

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Jonathan Allan · Answer 3 · 2016-08-22 04:20:39Z

Jelly, 28 26 25 24 bytes

QṚ,QyḊḊṖṖj@QµÐĿµJ’⁶ẋ⁸żYṚ

-4 bytes thanks to Dennis

Recipe:

QṚ,QyḊḊṖṖj@QµÐĿµJ’⁶ẋ⁸żYṚ - one argument: input()
Q  Q       Q             - set of Left=input(): "/\"
 Ṛ                       - reverse Left: "\/"
  ,                      - Left-pair-Right: ["\/","/\"]
     ḊḊṖṖ                - dequeue Left twice, then pop twice: input()[2:-2]
    y                    - translate Right with mapping in Left: swaps internal slashes
         j@              - join Right with separator Left (@ swaps operands)
            µ  µ         - chain separators to form a 1,1,1 chain of chains
             ÐĿ          - loop while results are unique and collect them
                J        - yield [1,...,len(Left=input())]
                 ’       - decrement: [0,....len(input())-1]
                  ⁶      - " "
                   ẋ     - repeat Left Right times: ["", " ", ...]
                    ⁸ż   - zip Right and Left (⁸ is the link's Left argument):
                                ...pads the loop results
                      Y  - joins Left with line-feeds
                       Ṛ - reverse Left

(serve with lemonade, those pyramids make for thirsty workers)

Cook up your own slash pyramid at TryItOnline, or try out all the OP's suggested tasters

xnor · Answer 4 · 2016-08-20 20:34:11Z

up vote 8 down vote

Python 2, 78 bytes

f=lambda s,p='\n':(s[2:]and f('/%s\\'%s.translate('/\\'*128)[2:-2],p+' '))+p+s

A recursive function that outputs a string. Each layer of the pyramid is appended to the recursive call with the layer above it. The prefix p, which starts as a newline character gains one more space to make the triangle. The next layer is produced by swapping slashes, cutting off the first and last two symbols, and sandwiching it inside a left and right slash.

Python 3 can save a byte by doing *99 in the translate, as the length-256 requirement was dropped.

answered yesterday

xnor

40.7k989228

Clever using translate, but do we not have to print? – Jonathan Allan yesterday

@JonathanAllan Not by default, you just have to output as the challenge says. – xnor yesterday

Thanks, I assumed, I now know. – Jonathan Allan yesterday

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Jonathan Allan · Answer 5 · 2016-08-20 22:49:56Z

up vote 7 down vote

Python 3, 108 104 101 94 91 89 88 bytes

b,f='\/';p=lambda t,n='\n':(t[2:]and p(f+''.join(map({f:b,b:f}.get,t[2:-2]))+b,n+' '))+n+t

-7 bytes thanks to xnor (letting me know we don't have to print!)
-3 bytes thanks to xnor (taking declaration outside of function declaration [d'oh])
-1 byte thanks to Dennis (replace f,b='/\\' with b,f='\/')

Test it on ideone. Note: input adjusted for double backslash (even raw strings won't work if they end in an odd number of backslashes).

edited yesterday

answered yesterday

Jonathan Allan

6587

You can jointly declare f,b='/\\' outside the function. – xnor yesterday

@xnor Thanks, I can't count ^^ – Jonathan Allan yesterday

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nimi · Answer 6 · 2016-08-20 21:09:58Z

up vote 6 down vote

Haskell, 98 94 90 85 bytes

q=init.tail
s '/'='\\'
s _='/'
t#""=t++"\\\n"
t#l=(' ':t)#(s<$>q l)++t++l#""
("/"#).q

Usage example (note: in Haskell backslashes within literal strings have to be escaped \\):

*Main> putStr $ (("/"#).q) "//\\\\///\\/\\"
    /\
   /\\\
  /\///\
 ///\\\/\
//\\///\/\

Simple recurse approach: # does the work by mapping s, which flips the / and \, on the inner elements. The additional parameter t keeps track of the indention level and is expanded by a space on each recursive call.

Note: the second recursive call of # (-> l#"") jumps directly to the base case and is just a short way to add l, \ and a newline, i.e. it replaces ++l++"\\\n".

Edit: @xnor saved 5 bytes. Thanks!

edited yesterday

answered yesterday

nimi

13.9k2743

l++"\\\n" looks like l#"". – xnor yesterday

1

An interesting way to swap two characters in a string s is [c|x<-s,c<-"ab",c/=x]. – xnor yesterday

@xnor: I've tried many things to get rid of the second ++"\\\n", but missed this one. Thanks! – nimi yesterday

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Neil · Answer 7 · 2016-08-20 19:32:20Z

up vote 5 down vote

JavaScript (ES6), 91 86 bytes

f=
(s,t=`
`)=>s[2]?f(`/${s.slice(2,-2).replace(/./g,c=>c>`/`?`/`:`\\`)}\\`,t+` `)+t+s:t+s
;

<input placeholder=Basis oninput=o.textContent=f(this.value)><pre id=o>

Output includes a leading newline character.

edited yesterday

answered yesterday

Neil

16.5k21049

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Jordan · Answer 8 · 2016-08-20 23:14:26Z

up vote 3 down vote

Ruby, 80 bytes

f=->s{s[-3]>?!&&f[" "+s.gsub(/^( *\/).|.(.$)?/){$1||$2||($&>?/??/:?\\)}]
puts s}

Ungolfed

f = ->s{
  s[-3] > ?! &&
    f[" " + s.gsub(/^( *\/).|.(.$)?/) {
      $1 || $2 || ($& > ?/ ? ?/ : ?\\)
    }]
  puts s
}

See it on ideone: http://ideone.com/HN0l0Y

edited yesterday

answered yesterday

Jordan

85829

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Neil · Answer 9 · 2016-08-21 00:18:31Z

Batch, 137 bytes

@echo off
if %1==/\ goto g
set s=%1
set s=\%s:~2,-2%/
set s=%s:/=-%
set s=%s:\=/%
set s=%s:-=\%
call %0 %s% "%~2 "
:g
echo %~2%1

Conveniently my use of%~2 and %1 means that I avoid having to spend bytes on setlocal. Explanation: Since Batch won't perform replacements on the empty string, we have to set up the next layer with the "wrong" edges, which will then be corrected as part of the string replacements.

Roland Illig · Answer 10 · 2016-08-21 11:44:55Z

Go, 300 bytes

package main
import(R"regexp";"os")
func p(b string)string{
s:=R.MustCompile(`^((\s*\S)(\S*)(\S))\s*`).FindStringSubmatch(b)
if len(s[3])>0{r:=""
for _,c:=range s[3][1:len(s[3])-1]{if c=='/'{r+=`\`}else{r+=`/`}}
return p(" "+s[2]+r+s[4])+s[1]+"\n"}
return s[1]+"\n"}
func main(){print(p(os.Args[1]))}

Long version:

package main

import (
    R "regexp"
    "os"
)

func pyramid(base string) string {
    m := R.MustCompile(`^((\s*\S)(\S*)(\S))\s*`).FindStringSubmatch(base)
    if len(m[3]) > 0 {
        reversed := ""
        for _, c := range m[3][1:len(m[3]) - 1] {
            if c == '/' {
                reversed += `\`
            } else {
                reversed += `/`
            }
        }
        return pyramid(" " + m[2] + reversed + m[4]) + m[1] + "\n"
    }
    return m[1] + "\n"
}
func main() {
    print(pyramid(os.Args[1]))
}

ruds · Answer 11 · 2016-08-22 04:10:32Z

05AB1E, 42 38 bytes

Dg;<FDDgÍ©£R®ÍN-£„/\DR‡'/ðN>×««R'\«}r»

Try it online!

Explanation:

# Read the input to the stack, loop for 0 .. len(input) / 2 - 1
Dg;<F
# Pop the stack and push it twice (to save the layer)
     D
# Save len(layer) - 2 to the top of the stack and register_c
      DgÍ©
# a = pop(); b = pop(); push(b[0:a].reverse())
# This removes the last 2 characters and reverses
          £R
# push(register_c - 2 - N)
            ®ÍN-
# a = pop(); b = pop(); push(b[0:a])
# This removes the leading spaces and the first two slashes
                £
# Push "/\" and "\/" to the stack.
                  „/\DR
# Transliterate the slashes
                       ‡
# Add N+1 spaces and a / to the end of the (reversed) current layer
                        '/ðN>×««
# Reverse the layer and add a \ to the end.
                                R'\«
# End the loop
                                    }
# Reverse the stack and join it with newlines. It is implicitly printed.
                                     r»

torcado · Answer 12 · 2016-08-22 07:28:14Z

><>, 186 179 175 bytes

0&v &+1&<
  >i:0)?^~&2,:&v
v'/'~v?:-1<  }0<
o    >84*o^-$;?=@:&:&}:: <
\&::&{:@+$}1+[{l1-$-2*:&1+{
>}1-:?!v$:l2%?!vo
^o'/'v?~e  (*5a<
^o'\'< >&:  ?v~]a'\'oo{1 ^
       ^&-1${<

oooh man this is definitely my largest ><> answer yet.

There's still probably some golfing left to be done (the bottom area is pretty wasteful)

Try it online

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The Great Pyramid of ASCII

Introduction

The task

Test cases

12 Answers 12

Retina, 59 56 54 52 bytes

Sample output

Pyth - 27 26 bytes

Jelly, 28 26 25 24 bytes

Python 2, 78 bytes

Python 3, 108 104 101 94 91 89 88 bytes

Haskell, 98 94 90 85 bytes

JavaScript (ES6), 91 86 bytes

Ruby, 80 bytes

Ungolfed

Batch, 137 bytes

Go, 300 bytes

05AB1E, 42 38 bytes

><>, 186 179 175 bytes

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current community

your communities

more stack exchange communities

The Great Pyramid of ASCII

Introduction

The task

Test cases

12 Answers 12

Retina, 59 56 54 52 bytes

Sample output

Pyth - 27 26 bytes

Jelly, 28 26 25 24 bytes

Python 2, 78 bytes

Python 3, 108 104 101 94 91 89 88 bytes

Haskell, 98 94 90 85 bytes

JavaScript (ES6), 91 86 bytes

Ruby, 80 bytes

Ungolfed

Batch, 137 bytes

Go, 300 bytes

05AB1E, 42 38 bytes

><>, 186 179 175 bytes

Your Answer

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