Code Golf: Build Me an Arc

Question

Code Golf: Build Me an Arc

1.8k views Asked by Jon Purdy At 29 July 2010 at 17:48

Challenge

The shortest program by character count that accepts standard input of the form X-Y R, with the following guarantees:

R is a non-negative decimal number less than or equal to 8
X and Y are non-negative angles given in decimal as multiples of 45° (0, 45, 90, 135, etc.)
X is less than Y
Y is not 360 if X is 0

And produces on standard output an ASCII "arc" from the starting angle X to the ending angle Y of radius R, where:

The vertex of the arc is represented by o
Angles of 0 and 180 are represented by -
Angles of 45 and 225 are represented by /
Angles of 90 and 270 are represented by |
Angles of 135 and 315 are represented by \
The polygonal area enclosed by the two lines is filled with a non-whitespace character.

The program is not required to produce meaningful output if given invalid input. Solutions in any language are allowed, except of course a language written specifically for this challenge, or one that makes unfair use of an external utility. Extraneous horizontal and vertical whitespace is allowed in the output provided that the format of the output remains correct.

Happy golfing!

Numerous Examples

Input:

0-45 8

Output:

        /
       /x
      /xx
     /xxx
    /xxxx
   /xxxxx
  /xxxxxx
 /xxxxxxx
o--------

Input:

0-135 4

Output:

\xxxxxxxx
 \xxxxxxx
  \xxxxxx
   \xxxxx
    o----

Input:

180-360 2

Output:

--o--
xxxxx
xxxxx

Input:

45-90 0

Output:

Input:

0-315 2

Output:

xxxxx
xxxxx
xxo--
xxx\
xxxx\

Original Q&A

There are 12 answers

bta On 30 July 2010 at 01:32

Ruby, 292 276 186 chars

x,y,r=gets.scan(/\d+/).map{|z|z.to_i};s=(-r..r);s.each{|a|s.each{|b|g=Math::atan2(-a,b)/Math::PI*180/1%360;print a|b==0?'o':g==x||g==y%360?'-/|\\'[g/45%4].chr: (x..y)===g ?'*':' '};puts}

Nicer-formatted version:

x, y, r = gets.scan(/\d+/).map{|z| z.to_i}
s = (-r..r)
s.each {|a|
    s.each {|b|
        g = (((Math::atan2(-a,b) / Math::PI) * 180) / 1) % 360
        print ((a | b) == 0) ? 'o' :
            (g == x || g == (y % 360)) ? '-/|\\'[(g / 45) % 4].chr :
                ((x..y) === g) ? '*' : ' '
    }
    puts
}

I'm sure someone out there who got more sleep than I did can condense this more...

Edit 1: Switched if statements in inner loop to nested ? : operator

Edit 2: Stored range to intermediate variable (thanks Adrian), used stdin instead of CLI params (thanks for the clarification Jon), eliminated array in favor of direct output, fixed bug where an ending angle of 360 wouldn't display a line, removed some un-needed parentheses, used division for rounding instead of .round, used modulo instead of conditional add

Jacob On 30 July 2010 at 07:09

MATLAB, 188 chars :)

input '';[w x r]=strread(ans,'%d-%d%d');l='-/|\-/|\-';[X Y]=meshgrid(-r:r);T=atan2(-Y,X)/pi*180;T=T+(T<=0)*360;T(T>w&T<x)=-42;T(T==w)=-l(1+w/45);T(T==x)=-l(1+x/45);T(r+1,r+1)=-'o';char(-T)

Commented code:

%%# Get the string variable (enclose in quotes, e.g. '45-315 4')
input ''
%%# Extract angles and length
[w x r]=strread(ans,'%d-%d%d');
%%# Store characters
l='-/|\-/|\-';
%%# Create the grid
[X Y]=meshgrid(-r:r);
%%# Compute the angles in degrees
T=atan2(-Y,X)/pi*180;
%%# Get all the angles
T=T+(T<=0)*360;
%# Negative numbers indicate valid characters
%%# Add the characters
T(T>w&T<x)=-42;
T(T==w)=-l(1+w/45);
T(T==x)=-l(1+x/45);
%%# Add the origin
T(r+1,r+1)=-'o';
%%# Display
char(-T)

Jon Purdy On 30 July 2010 at 16:12

Perl - 388 characters

Since it wouldn't be fair to pose a challenge I couldn't solve myself, here's a solution that uses string substitution instead of trigonometric functions, and making heavy use of your friendly neighbourhood Perl's ability to treat barewords as strings. It's necessarily a little long, but perhaps interesting for the sake of uniqueness:

($x,$y,$r)=split/\D/,<>;for(0..$r-1){$t=$r-1-$_;
$a.=L x$_.D.K x$t.C.J x$t.B.I x$_."\n";
$b.=M x$t.F.N x$_.G.O x$_.H.P x$t."\n"}
$_=$a.E x$r.o.A x$r."\n".$b;$x/=45;$y/=45;$S=' ';
sub A{$v=$_[0];$x==$v||$y==$v?$_[1]:$x<$v&&$y>$v?x:$S}
sub B{$x<=$_[0]&&$y>$_[0]?x:$S}
@a=!$x||$y==8?'-':$S;
push@a,map{A$_,'\\'.qw(- / | \\)[$_%4]}1..7;
push@a,!$x?x:$S,map{B$_}1..7;
eval"y/A-P/".(join'',@a)."/";print

All newlines are optional. It's fairly straightforward:

Grab user input.
Build the top ($a) and bottom ($b) parts of the pattern.
Build the complete pattern ($_).
Define a sub A to get the fill character for an angle.
Define a sub B to get the fill character for a region.
Build an array (@a) of substitution characters using A and B.
Perform the substitution and print the results.

The generated format looks like this, for R = 4:

DKKKCJJJB
LDKKCJJBI
LLDKCJBII
LLLDCBIII
EEEEoAAAA
MMMFGHPPP
MMFNGOHPP
MFNNGOOHP
FNNNGOOOH

Where A-H denote angles and I-P denote regions.

(Admittedly, this could probably be golfed further. The operations on @a gave me incorrect output when written as one list, presumably having something to do with how map plays with $_.)

AudioBubble On 30 July 2010 at 16:18

Ruby, 168 characters

Requires Ruby 1.9 to work

s,e,r=gets.scan(/\d+/).map &:to_i;s/=45;e/=45;G=-r..r;G.map{|y|G.map{|x|a=Math.atan2(-y,x)/Math::PI*4%8;print x|y!=0?a==s||a==e%8?'-/|\\'[a%4]:a<s||a>e ?' ':8:?o};puts}

Readable version:

start, _end, radius = gets.scan(/\d+/).map &:to_i
start /= 45
_end /= 45

(-radius..radius).each {|y|
    (-radius..radius).each {|x|
        angle = Math.atan2(-y, x)/Math::PI * 4 % 8
        print x|y != 0 ? angle==start || angle==_end%8 ? '-/|\\'[angle%4] : angle<start || angle>_end ? ' ' : 8 : ?o
    }
    puts
}

ninjalj On 30 July 2010 at 21:15

GNU BC, 339 chars

Gnu bc because of read(), else and logical operators.

scale=A
a=read()/45
b=read()/45
c=read()
for(y=c;y>=-c;y--){for(x=-c;x<=c;x++){if(x==0)if(y<0)t=-2else t=2else if(x>0)t=a(y/x)/a(1)else if(y<0)t=a(y/x)/a(1)-4else t=a(y/x)/a(1)+4
if(y<0)t+=8
if(x||y)if(t==a||t==b||t==b-8){scale=0;u=(t%4);scale=A;if(u==0)"-";if(u==1)"/";if(u==2)"|";if(u==3)"\"}else if(t>a&&t<b)"x"else" "else"o"};"
"}
quit

gwell On 31 July 2010 at 05:55

Lua, 259 characters

Slightly abuses the non-whitespace character clause to produce a dazzling display and more importantly save strokes.

m=math i=io.read():gmatch("%d+")a=i()/45 b=i()/45 r=i()for y=r,-r,-1 do for x=-r,r do c=m.atan2(y,x)/m.pi*4 c=c<0 and c+8 or c k=1+m.modf(c+.5)io.write(x==0 and y==0 and'o'or c>=a and c<=b and('-/|\\-/|\\-'):sub(k,k)or c==0 and b==8 and'-'or' ')end print()end

Input: 45-360 4

\\\|||///
\\\|||// 
\\\\|//  
--\\|/   
----o----
--//|\\--
////|\\\\
///|||\\\
///|||\\\

Able to handle odd angles

Input: 15-75 8

           |/////
          |//////
          |//////
          |//////
          ///////
         |//////-
         ////--- 
         //-     
        o

Dr. belisarius On 02 August 2010 at 02:25

Mathematica 100 Chars

Out of competition because graphics are too perfect :)

  f[x_-y_ z_]:=Graphics@Table[
                 {EdgeForm@Red,Disk[{0,0},r,{x °,y °}],{r,z,1,-1}]
                 SetAttributes[f,HoldAll]

Invoke with f[30-70 5]

Result

alt text http://a.imageshack.us/img80/4294/angulosgolf.png

alt text http://a.imageshack.us/img59/7892/angulos2.png

Note

The SetAttributes[f, HoldAll];

is needed because the input

    f[a-b c]

is otherwise interpreted as

    f[(a-b*c)]

gnovice On 03 August 2010 at 04:19

MATLAB 7.8.0 (R2009a) - 168 163 162 characters

Starting from Jacob's answer and inspired by gwell's use of any non-whitespace character to fill the arc, I managed the following solution:

[w x r]=strread(input('','s'),'%d-%d%d');
l='o -/|\-/|\-';
X=meshgrid(-r:r);
T=atan2(-X',X)*180/pi;
T=T+(T<=-~w)*360;
T(T>x|T<w)=-1;
T(r+1,r+1)=-90;
disp(l(fix(3+T/45)))

And some test output:

>> arc
0-135 4
\||||////
 \|||///-
  \||//--
   \|/---
    o----

I could reduce it further to 156 characters by removing the call to disp, but this would add an extra ans = preceding the output (which might violate the output formatting rules).

Even still, I feel like there are some ways to reduce this further. ;)

Anton Hansson On 11 August 2010 at 10:14

C# - 325 319 chars

using System;class P{static void Main(){var s=Console.ReadLine().Split(' ');
var d=s[0].Split('-');int l=s[1][0]-48,x,y,r,a=int.Parse(d[0]),b=int.Parse(d[1]);
for(y=l;y>=-l;y--)for(x=-l;x<=l;)Console.Write((x==0&&y==0?'o':a<=(r=((int)
(Math.Atan2(y,x)*57.3)+360)%360)&&r<b||r==b%360?
@"-/|\"[r/45%4]:' ')+(x++==l?"\n":""));}}

Newlines not significant.

Sample input/output

45-180 8
\||||||||////////
\\|||||||///////
\\\||||||//////
\\\\|||||/////
\\\\\||||////
\\\\\\|||///
\\\\\\\||//
\\\\\\\\|/
--------o

135-360 5
\
\\
\\\
\\\\
\\\\\
-----o-----
----/|\\\\\
---//||\\\\
--///|||\\\
-////||||\\
/////|||||\

BalusC On 21 August 2010 at 23:43

Java - 304 chars

class A{public static void main(String[]a){String[]b=a[0].split("-");int e=new Integer(b[1]),r=new Integer(a[1]),g,x,y=r;for(;y>=-r;y--)for(x=-r;x<=r;)System.out.print((x==0&y==0?'o':new Integer(b[0])<=(g=((int)(Math.atan2(y,x)*57.3)+360)%360)&g<e|g==e%360?"-/|\\".charAt(g/45%4):' ')+(x++<r?"":"\n"));}}

C (902 byte)

This doesn't use trigonometric functions (like the original perl version), so it's quite ``bloated''. Anyway, here is my first code-golf submission:

#define V(r) (4*r*r+6*r+3)
#define F for(i=0;i<r;i++)
#define C ;break;case
#define U p-=2*r+2,
#define D p+=2*r+2,
#define R *++p=
#define L *--p=
#define H *p='|';
#define E else if
#define G(a) for(j=0;j<V(r)-1;j++)if(f[j]==i+'0')f[j]=a;
#define O(i) for(i=0;i<2*r+1;i++){
main(int i,char**v){char*p,f[V(8)];
int j,m,e,s,x,y,r;p=*++v;x=atoi(p);while(*p!=45)p++;
char*h="0123";y=atoi(p+1);r=atoi(*++v);
for(p=f+2*r+1;p<f+V(r);p+=2*r+2)*p=10;
*(p-2*r-2)=0;x=x?x/45:x;y/=45;s=0;e=2*r;m=r;p=f;O(i)O(j)
if(j>e)*p=h[0];E(j>m)*p=h[1];E(j>s)*p=h[2];else*p=h[3];p++;}
if(i+1==r){h="7654";m--;e--;}E(i==r){s--;}E(i>r){s--;e++;}
else{s++;e--;}p++;}for(p=f+V(r)/2-1,i=0;i<r;i++)*++p=48;
for(i=0;i<8;i++)if(i>=x&&i<y){G(64);}else G(32);
y=y==8?0:y;q:p=f+V(r)/2-1;*p='o';switch(x){
C 0:F R 45 C 1:F U R 47 C 2:F U H C 3:F U L 92
C 4:F L 45 C 5:F D L 47 C 6:F D H C 7:F D R 92;}
if(y!=8){x=y;y=8;goto q;}puts(f);}

also, the #defines look rather ugly, but they save about 200 bytes so I kept them in, anyway. It is valid ANSI C89/C90 and compiles with very few warnings (two about atoi and puts and two about crippled form of main).

**ninjalj** · Accepted Answer · 2010-07-29T21:19:12+00:00

Perl, 235 211 225 211 207 196 179 177 175 168 160 156 146 chars

<>=~/-\d+/;for$y(@a=-$'..$'){print+(map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a),$/}

Perl using say feature, 161 149 139 chars

$ echo -n '<>=~/-\d+/;for$y(@a=-$'"'"'..$'"'"'){say map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a}' | wc -c
139
$ perl -E '<>=~/-\d+/;for$y(@a=-$'"'"'..$'"'"'){say map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a}'

Perl without trailing newline, 153 143 chars

<>=~/-\d+/;for$y(@a=-$'..$'){print$/,map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a}

Original version commented:

$_=<>;m/(\d+)-(\d+) (\d+)/;$e=$1/45;$f=$2/45; # parse angles and radius, angles are 0-8
for$y(-$3..$3){                               # loop for each row and col
    for$x(-$3..$3){
            $t=atan2(-$y,$x)/atan2 1,1;   # angle of this point
            $t+=8if($t<0);                # normalize negative angles
            @w=split//,"-/|\\"x2;         # array of ASCII symbols for enclosing lines
            $s.=!$x&&!$y?"o":$t==$e||$t==$f?$w[$t]:$t>$e&&$t<$f?"x":$";
            # if it's origin -> "o", if it's enclosing line, get symbol from array
            # if it's between enclosing angles "x", otherwise space
    }
    $s.=$/;
}
print$s;

EDIT 1: Inlined sub, relational and equality operators return 0 or 1.
EDIT 2: Added version with comments.
EDIT 3: Fixed enclosing line at 360º. Char count increased significantly.
EDIT 4: Added a shorter version, bending the rules.
EDIT 5: Smarter fix for the 360º enclosing line. Also, use a number as fill. Both things were obvious. Meh, I should sleep more :/
EDIT 6: Removed unneeded m from match operator. Removed some semicolons.
EDIT 7: Smarter regexp. Under 200 chars!
EDIT 8: Lots of small improvements:

Inner for loop -> map (1 char)
symbol array from split string -> qw (3 chars)
inlined symbol array (6 chars, together with the previous improvement 9 chars!)
Logical or -> bitwise or (1 char)
Regexp improvement (1 char)
Use arithmethic for testing negative angles, inspired by Jacob's answer (5 chars)

EDIT 9: A little reordering in the conditional operators saves 2 chars.
EDIT 10: Use barewords for characters.
EDIT 11: Moved print inside of loop, inspired by Lowjacker's answer.
EDIT 12: Added version using say.
EDIT 13: Reuse angles characters for fill character, as Gwell's answer does. Output isn't as nice as Gwell's though, that would require 5 additional chars :) Also, .. operator doen't need parentheses.
EDIT 14: Apply regex directly to <>. Assign range operator to a variable, as per Adrian's suggestion to bta's answer. Add version without the final newline. Updated say version.
EDIT 15: More inlining. map{block}@a -> map expr,@a.

TechQA.

Code Golf: Build Me an Arc

Challenge

Numerous Examples

There are 12 answers

Perl, 235 211 225 211 207 196 179 177 175 168 160 156 146 chars

Perl using say feature, 161 149 139 chars

Perl without trailing newline, 153 143 chars

Ruby, 292 276 186 chars

MATLAB, 188 chars :)

Commented code:

Perl - 388 characters

Ruby, 168 characters

GNU BC, 339 chars

Lua, 259 characters

Able to handle odd angles

Mathematica 100 Chars

Note

MATLAB 7.8.0 (R2009a) - 168 163 162 characters

C# - 325 319 chars

Java - 304 chars

C (902 byte)

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