ASCII Triangles

Question

Your task is to write a program or a function that prints an ASCII triangle. They look like this:

|\
| \
|  \
----

Your program will take a single numeric input n, with the constraints 0 <= n <= 1000. The above triangle had a value of n=3.

The ASCII triangle will have n backslashes (\) and vertical bars (|), n+1 lines and dashes (-), and each line will have an amount of spaces equal to the line number (0-based, ie first line is line 0) besides the ultimate line.

Examples:

Input:

4

Output:

|\
| \
|  \
|   \
-----

Input:

0

Output:

In this test case, the output must be empty. No whitespace.

Input:

1

Output:

|\
--

Input & output must be exactly how I specified.

This is code-golf, so aim for the shortest code possible!

Answer 1

C, 58 bytes

i;f(n){for(i=2*n;~i--;printf(i<n?"-":"|%*c\n",2*n-i,92));}

--

Thanks to @Steadybox who's comments on this answer helped me shave a few bytes in my above solution

Answer 2

Javascript (ES6), 97 85 81 75 74 bytes

n=>(g=(n,s)=>n?g(--n,`|${" ".repeat(n)}\\
`+s):s)(n,"")+"-".repeat(n&&n+1)

Turns out I wasn't using nearly enough recursion

f=n=>(g=(n,s)=>n?g(--n,`|${" ".repeat(n)}\\
`+s):s)(n,"")+"-".repeat(n&&n+1)

console.log(f(0))
console.log(f(1))
console.log(f(2))
console.log(f(3))
console.log(f(4))

Answer 3

05AB1E, 16 15 16 bytes

Saved a byte thanks to Adnan

FðN×…|ÿ\}Dg'-×»?

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Explanation

F       }         # for N in range [0 ... input-1]
 ðN×              # push <space> repeated N times
    …|ÿ\          # to the middle of the string "|\"
         Dg       # get length of last string pushed
           '-×    # repeat "-" that many times
              »   # join strings by newline
               ?  # print without newline

Answer 4

V, 18 17 16 bytes

1 byte saved thanks to @nmjcman101 for using another way of outputting nothing if the input is 0

é\é|ÀñÙá ñÒ-xÀ«D

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Hexdump:

00000000: e95c e97c c0f1 d9e1 20f1 d22d 78c0 ab44  .\.|.... ..-x..D

Explanation (outdated)

We first have a loop to check if the argument is 0. If so, the code below executes (|\ is written). Otherwise, nothing is written and the buffer is empty.

Àñ     ñ            " Argument times do:
  é\é|              " Write |\
      h             " Exit loop by creating a breaking error

Now that we got the top of the triangle, we need to create its body.

Àñ   ñ              " Argument times do:
  Ù                 " Duplicate line, the cursor comes down
   à<SPACE>         " Append a space

Now we got one extra line at the bottom of the buffer. This has to be replaced with -s.

Ó-                  " Replace every character with a -
   x                " Delete the extra '-'

---

This answer would be shorter if we could whatever we want for input 0

V, 14 13 bytes

é\é|ÀñÙá ñÒ-x

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Answer 5

Jelly, 14 bytes

’⁶x⁾|\jṄµ€Ṫ”-ṁ

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How it works.

’⁶x⁾|\jṄµ€Ṫ”-ṁ  Main link. Argument: n

        µ       Combine the links to the left into a chain.
         €      Map the chain over [1, ..., n]; for each k:
’                 Decrement; yield k-1.
 ⁶x               Repeat the space character k-1 times, yielding a string.
   ⁾\j            Join the character array ['|', '\'], separating by those spaces.
      Ṅ           Print the result, followed by a linefeed.
         Ṫ      Tail; extract the last line.
                This will yield 0 if the array is empty.
          ⁾-ṁ   Mold the character '-' like that line (or 0), yielding a string
                of an equal amount of hyphen-minus characters.  

Answer 6

C#, 93 bytes

n=>{var s=n>0?new string('-',n+1):"";while(n-->0)s="|"+new string(' ',n)+"\\\n"+s;return s;};

Anonymous function which returns the ASCII triangle as a string.

Full program with ungolfed, commented function and test cases:

using System;

class ASCIITriangles
{
    static void Main()
    {
      Func<int, string> f =
      n =>
      {
          // creates the triangle's bottom, made of dashes
          // or an empty string if n == 0
          var s = n > 0 ? new string('-', n + 1) : "";

          // a bottom to top process
          while ( n-- > 0)
          // that creates each precedent line
            s = "|" + new string(' ', n) + "\\\n" + s;

          // and returns the resulting ASCII art
          return s;
      };

      // test cases:
      Console.WriteLine(f(4));
      Console.WriteLine(f(0));
      Console.WriteLine(f(1));
    }
}

Answer 7

Python 2, 69 bytes

lambda x:'\n'.join(['|'+' '*n+'\\'for n in range(x)]+['-'*-~x*(x>0)])

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Answer 8

CJam, 24 22 21 bytes

Saved 1 byte thanks to Martin Ender

ri_{S*'|\'\N}%\_g+'-*

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Explanation

ri                     e# Take an integer from input
  _                    e# Duplicate it
   {                   e# Map the following to the range from 0 to input-1
    S*                 e#   Put that many spaces
      '|               e#   Put a pipe
        \              e#   Swap the spaces and the pipe
         '\            e#   Put a backslash
           N           e#   Put a newline
            }%         e# (end of map block)
              \        e# Swap the top two stack elements (bring input to the top)
               _g+     e# Add the input's signum to itself. Effectively this increments any 
                       e#  non-zero number and leaves zero as zero.
                  '-*  e# Put that many dashes

Answer 9

PowerShell, 51 67 bytes

param($n)if($n){1..$n|%{"|"+" "*--$_+"\"};write-host -n ('-'*++$n)}

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(Byte increase to account for no trailing newline)

Takes input $n and verifies it is non-zero. Then loops to construct the triangle, and finishes with a line of -. Implicit Write-Output happens at program completion.

Answer 10

bash + printf, 68 bytes

for((;i<$1;))
{
a=$a-
printf "|%$[i++]s\\\\\n"
}
[ $a ] && echo $a-

Use "bash program_name number" to run. Sample run:

bash-4.1$ bash triangle 0
bash-4.1$ bash triangle 1
|\
--
bash-4.1$ bash triangle 2
|\
| \
---
bash-4.1$ bash triangle 3
|\
| \
|  \
----

Answer 11

SmileBASIC, 51 bytes

INPUT N
FOR I=0TO N-1?"|";" "*I;"\
NEXT?"-"*(N+!!N)

Answer 12

Retina, 39 bytes

.*
$*
*\`(?<=(.*)).
|$.1$* \¶
1
-
-$
--

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Convert decimal input to unary. Replace each 1 with |<N-1 spaces>\¶, print, and undo replace. Replace each 1 with a hyphen, and the last hyphen with 2 hyphens. Tadaa!

Answer 13

Common Lisp, 89 86 bytes

Creates an anonymous function that takes the n input and prints the triangle to *standard-output* (stdout, by default).

Golfed

(lambda(n)(when(< 0 n)(dotimes(i n)(format t"|~v@t\\~%"i))(format t"~v,,,'-<~>"(1+ n))))

Ungolfed

(lambda (n)
  (when (< 0 n)
    (dotimes (i n)
      (format t "|~v@t\\~%" i))
    (format t "~v,,,'-<~>" (1+ n))))

I'm sure I could make this shorter somehow.

Answer 14

C 101 93 75 bytes

f(n){i;for(i=0;i++<n;)printf("|%*c\n",i,92);for(;n--+1;)prin‌​tf("-");}

Ungolfed version

void f(int n)
{
  int i;

  for(i=0;i++<n;)
    printf("|%*c\n",i,92);

  for(;n--+1;)
    printf("-");

}

@Steadybox Thanks for pointing out, makes a lot of sense.

Answer 15

Python 3, 60 bytes

f=lambda n,k=0:k<n and'|'+' '*k+'\\\n'+f(n,k+1)or'-'[:n]*-~n

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Two more solutions with the same byte count.

f=lambda n,k=0:n and'|'+' '*k+'\\\n'+f(n-1,k+1)or-~k*'-'[:k]
f=lambda n,s='|':-~n*'-'[:n]if s[n:]else s+'\\\n'+f(n,s+' ')

Answer 16

dc, 98 bytes

256?dse1+d[q]st1=t^124*23562+dsaP2sk[[lkd256r^32*la+dsaPd1+skle>y]srle1<r]dsyx[45Ple1-dse0!>q]dsqx

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Explanation

This takes due advantage of dc's P command, which utilizes conversion to base 256 on most systems. Therefore, for any input n, the program first raises 256 to the n + 1th power, multiplies the result by 124 (ASCII character |), and then adds 256*92+10=23562 to the product (where 92 is equivalent to the character \ and 10 is the decimal value of the new-line (\n)). This results in a decimal number that when converted to base 256 with P results in the output |\\n where \n is the literal new-line character. A duplicate of this decimal number is also stored on top of register a.

Then, a "macro-loop" is invoked, as long as n > 1, in which a counter is incremented until n, beginning from 2, and, as the 3rd through nth base 256 digits are unset, 256 is raised to each of those increments, a result which is then multiplied by 32 (the ASCII single space character). Then the value on top of register a is incremented by the resulting product, thus, on each iteration, setting each one of the unset base 256 digits in the between the | and the \ characters to a single space.

Finally, after all n-1 lines have been output, another "macro-loop" is invoked in which all the n+1 dashes are output through the feeding of 45 to P on each iteration.

Note: The [q]st1=t segment makes sure that nothing is output for the input 0 by checking if the incremented input is equal to one, and if it is, simply executes the macro [q] which exits the program.

Answer 17

Charcoal, 15 bytes

Ｎβ¿β«↓β→⁺¹β↖↖β»

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Breakdown

Ｎβ¿β«↓β→⁺¹β↖↖β»
Ｎβ               assign input to variable β
   ¿β«         »  if β != 0:
      ↓β           draw vertical line β bars long
        →⁺¹β       draw horizontal line β+1 dashes long
            ↖      move cursor up one line and left one character
             ↖β    draw diagonal line β slashes long

Answer 18

Japt, 20 bytes

Saved 2 bytes thanks to @ETHproductions

o@'|+SpX +'\Ãp-pUÄ)·

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Explanation

o@'|+SpX +'\Ãp-pUÄ)·
o                       // Creates a range from 0 to input
 @                      // Iterate through the array
  '|+                   // "|" + 
     SpX +              // S (" ") repeated X (index) times +
          '\Ã            // "\" }
             p-pU       // "-" repeated U (input) +1 times
                 Ä)·    // Join with newlines

Answer 19

J, 20 bytes

-13 bytes thanks to bob

*#' \|-'{~3,~2,.=@i.

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original: 33 bytes

(#&'| \'@(1,1,~])"0 i.),('-'#~>:)

ungolfed

(#&'| \' @ (1,1,~])"0 i.) , ('-'#~>:)

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Answer 20

Commodore BASIC (C64/128, TheC64 & Mini, VIC-20, PET, C16/+4) - 46 BASIC Bytes

0inputn:ifnthenfori=1ton:?"{shift+B}{left}"spc(i)"{shift+M}":next:fori=.ton:print"-";:next

There is a sanity check for zero, but any other positive integer will work.

Note, a C64 has 25 rows and 40 columns text (some PETs and the C128 in VDC mode has 80 columns, the VIC-20 is 22 columns by 23 rows) so the output will be skewed if you exceed the screen limit in either direction.

I've added a screenshot so that you may see the PETSCII characters that I can't make happen in this listing.

Answer 21

Pyke, 18 17 bytes

I Fd*\|R\\s)Qh\-*

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Answer 22

Python2, 73 bytes

n=input()
w=0
exec'print"|"+" "*w+"\\\\"+("\\n"+"-"*-~n)*(w>n-2);w+=1;'*n

A full program. I also tried string interpolation for the last line, but it turned out be a couple bytes longer :/

exec'print"|%s\\\\%s"%(" "*w,("\\n"+"-"*-~n)*(w>n-2));w+=1;'*n

Another solution at 73 bytes:

n=j=input()
exec'print"|"+" "*(n-j)+"\\\\"+("\\n"+"-"*-~n)*(j<2);j-=1;'*n

Test cases

0:

1:
|\
--

2:
|\
| \
---

3:
|\
| \
|  \
----

6:
|\
| \
|  \
|   \
|    \
|     \
-------

Answer 23

MATL, 19 bytes

?'\|- '2GXyYc!3Yc!)

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?         % Implicit input. If non-zero
  '\|- '  %   Push this string
  2       %   Push 2
  G       %   Push input
  Xy      %   Identity matrix of that size
  Yc      %   Prepend a column of 2's to that matrix
  !       %   Transpose
  3       %   Push 3
  Yc      %   Postpend a column of 3's to the matrix
  !       %   Transpose
  )       %   Index into string
          % Implicit end. Implicit display

Answer 24

QBIC, 41 bytes

:~a>0|[a|?@|`+space$(b-1)+@\`][a+1|Z=Z+@-

Explanation

:~a>0|  Gets a, and checks if a > 0
        If it isn't the program quits without printing anything
[a|     For b=1; b <= a; b++
?@|`+   Print "|"
space$  and a number of spaces
(b-1)   euqal to our current 1-based line - 1
+@\`    and a "\"
]       NEXT
[a+1|   FOR c=1; c <= a+1; c++
Z=Z+@-  Add a dash to Z$
        Z$ gets printed implicitly at the end of the program, if it holds anything
        The last string literal, IF and second FOR loop are closed implicitly.

Answer 25

R, 101 bytes

for(i in 1:(n=scan())){stopifnot(n>0);cat("|",rep(" ",i-1),"\\\n",sep="")};cat("-",rep("-",n),sep="")

This code complies with the n=0 test-case if you only consider STDOUT !
Indeed, the stopifnot(n>0) part stops the script execution, displays nothing to STDOUT but writes Error: n > 0 is not TRUE to SDTERR.

Ungolfed :

for(i in 1:(n=scan()))
    {
    stopifnot(n>0)
    cat("|", rep(" ", i-1), "\\\n", sep = "")
    }

cat("-", rep("-", n), sep = "")

Answer 26

Python 2, 62 bytes

n=input();s='\\'
exec"print'|'+s;s=' '+s;"*n
if n:print'-'*-~n

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Prints line by line, each time adding another space before the backslash. If a function that doesn't print would be allowed, that would likely be shorter.

Answer 27

JavaScript (ES6), 71 bytes

f=
n=>console.log(' '.repeat(n).replace(/./g,'|$`\\\n')+'-'.repeat(n+!!n))

<form onsubmit=f(+i.value);return!true><input id=i type=number><input type=submit value=Go!>

Outputs to the console. Save 6 bytes if printing to the SpiderMonkey JavaScript shell is acceptable. Save 13 bytes if returning the output is acceptable.

Answer 28

Befunge-98, 68 bytes

&:!#@_000pv<
:kg00 ',|'<|`g00:p00+1g00,a,\'$,kg00
00:k+1g00-'<@,k+1g

Answer 29

Python 2, 67 bytes

Another function in Python 2, using rjust.

lambda n:('|'.join(map('\\\n'.rjust,range(n+2)))+'-'*-~n)[4:]*(n>0)

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Answer 30

Perl, 63 bytes

$n=shift;print'|',$"x--$_,"\\\n"for 1..$n;print'-'x++$n,$/if$n

Ungolfed:

$ perl -MO=Deparse triangle.pl
$n = shift @ARGV;
print '|', $" x --$_, "\\\n" foreach (1 .. $n);
print '-' x ++$n, $/ if $n;

$" is the list separator, which defaults to " ". $/ is the output record separator, which defaults to "\n". $_ is the implicit loop variable.