Generate a right triangle

Question

In this challenge, you must take two numbers (separated by a space) as input and output an ASCII right triangle, made up of xs.

The first number will be the width and height of the triangle you should output. The second number will be which corner the right angle will be in. The corners are numbered 1 to 4, starting in the top left and going in English reading order:

1    2



3    4

For example (inputs and their respective triangle outputs):

INPUT | 3 1 | 3 2 | 3 3 | 3 4
------+-----+-----+-----+----
 OUT- | xxx | xxx | x   |   x
 PUT  | xx  |  xx | xx  |  xx
      | x   |   x | xxx | xxx

Your program's output must match these examples exactly for their respective inputs.

The input will always be valid: the first number will be an integer ≥1, and the second number will be 1, 2, 3, or 4.

This is code-golf; shortest code (in character count) wins.

Answer 1

APL (30)

{' x'[1+(⍎⍵⌷'⌽+⍉⊖')≤/¨⍳2⍴⍺]}/⎕

Explanation:

• {...}/⎕: reduce given function over the input (so if the input has 2 numbers, just calls the function with those two numbers, ⍺ being the left number and ⍵ the right number)
• ≤/¨⍳2⍴⍺: Make an ⍺-by-⍺ coordinate matrix and set those positions where the X coordinate is not greater than the Y coordinate, giving a bitfield.
• (⍎⍵⌷'⌽+⍉⊖'): select a transformation function given by ⍵ to put the triangle right-side-up.
• ' x'[1+...]: add one to the bitfield, and use the result as an index into the string ' x', so putting space for 0 and x for 1.

Answer 2

Ruby, 116 115 109 96

I shall start with my own solution.

i=gets.split
s=i[0].to_i
(i[1]<?3?s.downto(1):1..s).map{|x|t=?x*x
puts /2|4/=~i[1]?t.rjust(s):t}

I just know that I'll get beat by a 30 character GolfScript solution almost instantly :P

Thanks to minitech for shaving off 19 characters (wow)!

Answer 3

GolfScript (34 33 chars)

~\:^,{)' x'^*$>^<0(2$?%}%\(2&(%n*

It's a shame that the corners aren't numbered in rotation, because that would allow a more elegant approach of building one array and then rotating it n times:

~\:^,{)' x'^*$>^<}%{-1%zip}@)*n*

Answer 4

C# - 195

using System;class P{static void Main(string[]a){int G=int.Parse(
a[0]),O=int.Parse(a[1]),L=O<3?0:G+1,F=O<3?-G:1;G=O%2>0?-G:G;for(;
F<L;F++)Console.Write("{0,"+G+"}\n","".PadRight(F<0?-F:F,'x'));}}

Formatted:

using System;
class P
{
    static void Main(string[] a)
    {
        int G = int.Parse(a[0]),
            O = int.Parse(a[1]),
            L = O < 3 ? 0 : G + 1,
            F = O < 3 ? -G : 1;

        G = O % 2 > 0 ? -G : G;

        for(; F < L; F++)
            Console.Write("{0," + G + "}\n", "".PadRight(F < 0 ? -F : F, 'x'));
    }
}

Answer 5

Mathematica 122 (104?)

g@s_ := ({w, p} = ToExpression@StringSplit@s; 
   Array[If[Switch[p, 1, # <= (w + 1 - #2), 2, # <= #2, 3, # >= #2, 4, # > (w - #2)],
   "X", ""] &, {w, w}]) // Grid

---

GraphicsGrid[{{g["12 1"], g["12 3"]}}]

---

Under a liberal interpretation of "output", the following (104 chars) will work.

f@s_ := ({w, p} = ToExpression@StringSplit@s; 
  Graphics[Polygon@Delete[{{w, 0}, {0, 0}, {w, w}, {0, w}}, p], Axes -> True])


f["50 4"]

---

If input in the form of a list were permitted, the following (75 chars) would suffice:

f[{w_, p_}] := 
 Graphics[Polygon@Delete[{{w, 0}, {0, 0}, {w, w}, {0, w}}, p], Axes -> True]

---

Answer 6

Golfscript, 39 36 35 characters

~\:y,{' '*'x'y*+y<0~2$?%}%-1@2>?%n*

live demo: http://golfscript.apphb.com/?c=OyczIDInCn5cOnkseycgJyoneCd5Kit5PC0xIDIkPyV9JS0xQDI%2BPyVuKgo%3D

too bad it's not 30 characters as requested

Answer 7

J, 59 55 42 38 37 36 characters

If it's permitted to have the input at the end of the program:

(|:@|.@]^:([:|[+_7*2<[)[:[\'x'$~])~/

If not (for an extra 3 characters):

t=.(|:@|.@]^:([:|[+_7*2<[)[:[\'x'$~])~/

Usage:

   (|:@|.@]^:([:|[+_7*2<[)[:[\'x'$~])~/3 4
  x
 xx
xxx

or

   t 3 4
  x
 xx
xxx

I think this could be a fair bit shorter since most of the characters are brackets and caps to keep it in an implicit style.

Edit
Using a gerund and the agenda verb has chopped off a few characters, but there's still too many caps in there for my liking.

Edit 2
That's a bit more like it. Dumping the agenda for a list of how many rotations are required gets rid of most of the extra brackets and a few caps.

Edit 3
Got rid of the last extraneous cap and a pair of brackets in the process. Need to find a cheaper way of encoding the number of rotations required.

Edit 4 Use prefix instead of suffix to chop off a character. Enables a different way of creating the list which doesn't save any characters. Bugger.

Edit 5
Using a formula to chop off another character. Still feel this bit could be shorter.

Answer 8

Python 106 Characters

w,d=map(int,raw_input().split())
for e in range(1,w+1)[::d/3*2-1]:print('%'+'-+'[d%2]+str(w)+'s')%('*'*e)

Answer 9

Python 3, 91

Based on Abhijit's answer.

Modified the creation of the output string to avoid the sum of strings and the ugly 1s in the range. Python 3 gets rid of the raw_ in raw_input, but makes necessary to use // for integer divison and to add parantheses for print, so that saves only one character.

w,d=map(int,input().split())
for e in range(w)[::d//3*2-1]:print('%*s'%(w-d%2*2*w,'x'*-~e))

Answer 10

Kitten, 140

def s{><replicate}
getLine{' 'neChar}span{readInt fromSome}toBoth->{w n}
w 0 if(n 2>){><}..
{<>w>< -{'X's}{' 's}both if(n 2%0=){><}cat say}each

Ungolfed:

getLine
{' ' neChar} span
{readInt fromSome} toBoth
->{ width corner }

width 0
if (corner 2 >):
  swap
..

{ ->index
  'X' index replicate
  ' ' (width index -) replicate
  if (corner 2 % 0 =):
    swap
  cat say
} each

Evidence that I need to implement overloading and flesh out the standard library.