Chessboard pattern

Question

Input: a positive number, smaller then 80, from stdin or as a command-line argument.

Output: A square chessboard pattern, the size of the input number. The dark fields are represented by the letter 'X', the white fields by a space. The top-left field should be 'X'.

A complete program is required.

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Examples:

Input: 1

Output:

X

Input: 8

Output:

X X X X 
 X X X X
X X X X 
 X X X X
X X X X 
 X X X X
X X X X 
 X X X X

Answer 1

Pyth, 13 chars

Note: Pyth is much too new to be eligible to win. However, it was a fun golf and I thought I'd share it.

VQ<*QX*d2N\XQ

Try it here.

How it works:

                       Q = eval(input())
VQ                     for N in range(Q):
  <         Q                                                        [:Q]
   *Q                                    (Q*                        )
     X*d2N\X                                assign_at(" "*2, N, "X")

Basically, this uses X to generate "X " or " X" alternately, then repeats that string Q times, and takes its first Q characters. This is repeated Q times.

How does the X (assign at) function work? It takes the original string, " " in this case, an assignment location, N in this case, and a replacement character, "X" in this case. Since Pyth's assignments are modular, this replaces the space at location N%2 with an X, and returns the resultant string, which is therefore "X " on the first, third, etc. lines, and " X" on the others.

Answer 2

Golfscript - 17 chars

~:N,{"X "N*>N<n}%

Analysis

~ convert input to an int
:N store in the variable N
,{...} for each value of [0...N-1]
"X "N* repeat "X " to give a string of N*2 characters
> take the substring starting from the loop index...
N< ...ending N characters later
n put a newline a the end of each string

Answer 3

Perl, 41 40

for$i(1..$_){say substr" X"x$_,$i%2,$_}

Perl 5.10 or later, run with perl -nE 'code' (n counted in code size)

Sample output:

$ perl -nE'for$i(1..$_){say substr" X"x 40,$i%2,$_}' <<<5
X X X
 X X
X X X
 X X
X X X
$ perl -nE'for$i(1..$_){say substr" X"x 40,$i%2,$_}' <<<8
X X X X
 X X X X
X X X X
 X X X X
X X X X
 X X X X
X X X X
 X X X X

Answer 4

Python, 48 Characters

x,i=input(),0
exec'print(x*"X ")[i:i+x];i^=1;'*x

Answer 5

Python, 76 characters

n=input()
p='X '*n
print n/2*(p[:n]+'\n'+p[1:n+1]+'\n'),
if n&1:print p[:n]

Answer 6

Scala - 141 95 characters

var a=args(0).toInt
for(y<-1 to a;x<-1 to a)print((if((x+y)%2<1)"X"else" ")+("\n"*(x/a)take 1))

Usage: scala filename N where n is your input to the program.

Answer 7

APL (16)

Assuming ⎕IO=0 (i.e. zero-indexed arrays, it is a setting)

' X'[=/¨2⊤¨⍳2⍴⎕]

Explanation:

• ⍳2⍴⎕: read a number N, and create a N×N matrix containing (0,0) to (N-1,N-1).
• 2⊤¨: get the least significant bit of each number in the matrix. (So now we have (0,0), (0,1), (0,0)... (1,0), (1,1), (1,0)...)
• =/¨: for each pair, see if the two numbers are equal. (Now we have 1 0 1 0 1 0 ...)
• ' X'[...]: put a space for each 0 and an X for each 1.

Answer 8

Ruby 45 42

(x=gets.to_i).times{|i|puts ("X "*x)[i,x]}

Demo: http://ideone.com/Mw25e

Answer 9

Python

48 Chars

EDIT: Kinda Wrong...There's an extra space at the end...but thats not visible. If you change the space to "O" (or any nonwhitespace char) then modify [i%2:n] to [i%2:n+i%2]. for the correct version.

n=input()
i=0;
while i<n:print('X '*n)[i%2:n];i+=1

Answer 10

C++ - 253 obfuscated characters

#include <iostream.h>
int main(int i,char*c[]=0)
{
  char a=i,b=i>>8;i&32512?((i>>16&255)<a)?(cout<<b)?main((i^30720)+65536):0:(cout<<endl)?(((b=(i>>24)+1)<a)?main((i&2130706559)+((b&1)?16785408:16799744)):0):0:main((i>=2?atoi(1[c]):8)|22528);
}

Answer 11

JavaScript, 169

function b(w){var i=w,j=w,r='';while(i--){while(j--){if((i+j)%2)r+=' ';else r+='X'}j=w;r+="\n"}return r}do{n=parseInt(prompt('Number'))}while(isNaN(n)||n<1);alert(b(n));

Answer 12

Java 10, lambda function, 92 87 84 bytes

n->{for(int i=0;i<n*n;)System.out.print(((i%n+i/n)%2<1?"X":" ")+(++i%n<1?"\n":""));}

Try it online here.

Thanks to ceilingcat for golfing 4 bytes and to Kevin Cruijssen for golfing 3 more.

Ungolfed version:

n -> { // void lambda taking an int as argument
    for(int i = 0; i < n*n; ) // loop over the entire square
            System.out.print(((i%n + i/n) % 2 < 1 ? "X" : " ") // print an 'X' or a space depending on which line&column we're on
               + (++i % n < 1 ? "\n" : "")); // print a newline at the end of a line
}

Java 8, full program, 155 139 bytes

interface M{static void main(String[]a){int i=0,n=new Byte(a[0]);for(;i<n*n;)System.out.print(((i%n+i/n)%2<1?"X":" ")+(++i%n<1?"\n":""));}}

Try it online here.

Ungolfed version:

interface M {
    static void main(String[] a) {
        int i = 0, // iterator variable for the loop
            n = new Byte(a[0]); // take the argument and convert it to an int
        for(; i < n*n; ) // loop over the entire square
            System.out.print( ((i%n + i/n) % 2 < 1 ? "X" : " ") // print an 'X' or a space depending on which line&column we're on
                             +(++i % n < 1 ? "\n" : "") ); // print a newline at the end of a line
        }
    }
}

Answer 13

Japt, 8 7 bytes

ÆîSi'XY

Run it online

7 6 bytes if we can replace X with x:

ÆîSixY

Run it online

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Alternative 8 byte solution:

Æî"X "éY

Run it online

Answer 14

Scala, 68 bytes

  def^(n:Int)=for(a<-1 to n)println(("x_"*n).substring(n%2+1,n+n%2+1))

or

  def^(n:Int)=for(a<-1 to n)println(("x_"*n).substring(a%2+1).take(n))

Try it online!

Answer 15

Brainfuck, 140 bytes

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

Answer 16

MATL, 9 bytes

:&+o~88*c

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ASCII c 88 multiplied * by not ~ the parity o of the broadcast self-addition &+ of the range : from 1 to the input.

Answer 17

Javascript, 67 bytes

for(j=n=readline()|0;j--;)console.log(' X'.repeat(n).substr(j%2,n))

Try it online

C, 83 bytes

i,j;main(n){for(scanf("%d",&n);i++<n;puts(""))for(j=0;j<n;)putchar(i+j++&1?88:32);}

Try it online

Basic C64, 89 bytes

1 INPUTN:FORI=1TON;FORJ=1TON:IFI+JAND1THENPRINT" ";:GOTO3
2 PRINT"X";
3 NEXT:PRINT"":NEXT

Answer 18

Scala, 40 and 54

The number of characters is 40 for a function, 54 for a complete program.

The solution giving only a function body is:

("X "*n)sliding n take n foreach println

Try it online

 

The solution giving a complete program is:

val n=readInt;("X "*n)sliding n take n foreach println

You can run it using the following command line.

scala -e 'val n=readInt;("X "*n)sliding n take n foreach println' <<< 8

where 8 is the input.

Answer 19

k (26 chars)

26 For bare function:

{-1',/x#',x#'("X ";" X");}

Or a further 7 to take input from stdin

{-1',/x#',x#'("X ";" X");}"I"$0:0

Answer 20

Bash: 60 characters

yes X|fmt -w80|paste -d '' <(yes '
 ') -|head -$1|cut -c1-$1

The table size is passed as command-line parameter, for example bash chesstable.sh 8.

Answer 21

APL (Dyalog Extended), 12 bytes^SBCS

Anonymous tacit prefix function. Requires ⎕IO←0 (zero-based indexing).

'X '⊇⍨2|⍳+⍀⍳

Try it online!

⍳ ɩndices 0…n–1

+⍀ plus table with that horizontally and vertically:

 ⍳ ɩndices 0…n–1

2| division remainder when divided by two

'X '⊇⍨ use that matrix to index into the string

Answer 22

Python - 127 characters

from sys import*
r=stdout.write
s=int(raw_input())
[[r((x+y+1)%2 and"x"or" ")for x in range(s)]and r("\n")for y in range(s)]

Answer 23

C - 92 86

i,j;main(n){for(scanf("%d",&n);i<n;puts(""),i++)for(j=0;j<n;j++)putchar("X "[i+j&1]);}

Answer 24

PHP, 75 bytes

for(;@$i++<$k=$argv[1];){for($j=0;$j++<$k;)echo($i+$j)%2?' ':'X';echo"\n";}

Answer 25

Japt v1.4.6 -R, 10 bytes

Æç"X " tXU

Try it

-3 bytes thanks to @Shaggy!

Æç"X " tXU   # full program
Æ            # generate a range of numbers based on input
             # and map each number through a function 
 ç"X "       # inside the function, repeat "X " a bunch of times
       tXU   # select a substring from the "X " repeated string
             # The -R flag joins the array with new lines

Answer 26

Canvas, 6 bytes

XX＼ｍ⤢ｍ

Try it here!

Answer 27

Python 2, 47 bytes

n=input()
s='X '*n
exec"print s[:n];s=s[1:];"*n

Try it online!

---

Python 2, 47 bytes

n=input()
i=0
exec"i^=1;print'X'*i+n/2*' X';"*n

Try it online!

Trims trailing space.

Answer 28

C# (Visual C# Interactive Compiler), 63 bytes

x=>{for(int i=x++*x;--i>0;)Write(" X\n"[i%x<1?2:(i/x+i%x)%2]);}

Try it online!

Answer 29

PowerShell, 39 bytes

param($n)1..$n|%{' X'*$n|% S*g($_%2)$n}

Try it online!

Answer 30

Unexpanded Sinclair ZX-81/Timex TS-1000/1500 and compatibles, ~96 Tokenized BASIC bytes

 1 LET X$="X X X X X X X X X X X "
 2 INPUT I
 3 FOR X=SGN PI TO I
 4 PRINT X$( TO I)
 5 LET X$=X$(VAL "2" TO )+X$(SGN PI)
 6 NEXT X

There are some limitations here; as the Sinclair ZX-81 by default only allows 32 character per line, and only 22 lines per screen by default, I have limited the maximum "chess board" to that, 22 x 22.

I is used here as a user input variable to determine the required "size" of the chess board. Once entered into the loop, the X$ string is essentially shifted to the right by one character in line 5.

Enjoy typing!

Answer 31

C64/128 and C64Mini (and compatibles), 68 tonekized BASIC bytes

 0fOi=0to11:a$=a$+"V ":nE:inputi:fOx=1toi:?leF(a$,i):a$=rI(a$,21)+leF(a$,1):nE

I've limited the potential size of the chess board pattern to a width of 22 because whilst the C64 might have 40 text columns, it only has 25 rows and therefore going over 22 will mean that some of the pattern is lost because when exiting a symbolic listing the C64 with typically add a carriage return, then the ready. prompt, and another carriage return where the cursor will reside.

To explain, here is the non-obfuscated symbolic listing:

 0 for i=0 to 11
 1  let a$=a$+"V "
 2 next i
 3 input i
 4 for x=1 to i
 5  print left$(a$, i)
 6  let a$=right$(a$, 21)+left$(a$, 1)
 7 next x

First the chess board patters is built in the a$ variable with the shifted (or uppercase) v representing an X.

The user is then asked for an input of a numeric value. This will work with positive Integers with a greater value than zero, though will work also with positive floating point numbers greater or equal to one.

A for/next loop is set up to the Integer value of the number entered, printing out the pattern to the length of the number entered.

The a$ variable is then shuffled one character to ensure the chess board effect in the loop.

Enjoy programming!

Answer 32

K (oK), 19 bytes

Solution:

{x$(x;x+~2!x)#"X "}

Try it online!

Explanation:

Reshape the input with an odd-length so that the X_ wraps to create the checkerboard, and then truncate to the correct width:

{x$(x;x+~2!x)#"X "} / the solution
{                 } / lambda taking implicit input x
              "X "  / string "X "
   ( ;      )#      / reshape to (length;width)
         2!x        / x mod 2
        ~           / not (0=>1, 1=>0)
      x+            / add to x
    x               / length is input
 x$                 / pad width to x

Answer 33

Scala, 84 bytes

for(i<-1 to a;s=Seq.fill((a+1)/2)("X ").mkString)println(if(i%2==1)s else s.reverse)

Try it online!

Answer 34

CJam, 18 bytes

I probably could have just ported the GolfScript answer, but here is a different approach. (And CJam is not eligible for winning anyway.)

l~,_f{f{+2%S'X?}N}

Test it here.

The idea is to iterate over the 2D grid with x and y indices on the stack, using the f{f{...}} trick. Given x and y, we can simply determine black and white as (x+y)%2 and use that to pick between the character X and a string containing a space.

Answer 35

J, 21 chars

J was missing too.

   ([:u:32+56*=/~@$&1 0) 5
X X X
 X X 
X X X
 X X 
X X X

Previous, 22 chars:

Char codes from mod2 pattern of row # + column #:

   ([:u:88-56*2&|@+/~@i.) 5

Answer 36

Q, 33

{$[1=x mod 2;x;x-1]cut(x*x)#"X "}

Answer 37

Ruby 58

i=ARGV[0].to_i
1.upto(i*i){|n|print n%i==0?"\n":' x'[n%2]}

Answer 38

VB.net, 161

Module C
   Sub Main()
     Dim n As Integer
     If Integer.TryParse(Console.ReadLine,n) Then
     For x=1To n
        For y=1To n
          Console.Write("* "((x+y)Mod 2))
        Next
        Console.WriteLine()
      Next
     End If
    End Sub
End Module

Answer 39

PHP - 136 chars (without whitespace)

Allows for x and y function input.

Also supports odd inputs now.

If you style the output to have 0.65 em line-height and change this ▒█ and █░ to □■ and ■□ then it comes out looking like a real (square) chessboard.

Code:

function gen_cb($x,$y)
{
$c=0;
$y*=2;
for($i=0;$i<$y;$i++){
for($j=0;$j<$x;$j++){
echo $c%2==0 ? "░█" : "█░";
}
echo "<br/>";
$c++;
}
}
gen_cb(7,7);

Output:

░█░█░█░█░█░█░█
█░█░█░█░█░█░█░
░█░█░█░█░█░█░█
█░█░█░█░█░█░█░
░█░█░█░█░█░█░█
█░█░█░█░█░█░█░
░█░█░█░█░█░█░█

Answer 40

PHP, 87

for($x=0;$x<$m=$argv[1];$x++){echo"\n";for($y=0;$y<$m;$y++)echo($y^($x%2))%2?' ':'X';}

Answer 41

cQuents, 17 bytes

|
&"X "Tn/2,Z[1:]

Try it online!

Explanation

|
                     Separate terms on newline
 &                   Given input n, output first n terms in sequence
                     Odd terms equal
  "X "                               "X "
      *              implicit             repeated                  times
      T                                            ceiling of 
       n/2                                                    n / 2         
          ,          Even terms equal
           Z                          previous term
            [1:]                                    with the first character removed (Python slice notation)

Answer 42

Charcoal, 10 bytes

Ｅθ⭆θ§X ⁺ιλ

Try it online! Link is to verbose version of code.

Explanation

Ｅθ           Map over first input (predefined variable). Since it's a number, maps over 0 to input (excluding upper bound) instead
   ⭆θ        String map over first input
      §  ⁺ιλ  At (cyclic) index i + l (current loop variable for inner and outer loop respectively)
       X      The string "X ". Note there is a space after the "X"

Answer 43

05AB1E, 13 bytes

„X ׂεI∍}I∍»

Can definitely be golfed a bit more..

Try it online or verify some more test cases.

Explanation:

„X ×           # Repeat string "X " the (implicit) input amount of times
    ‚         # Pair it with its reverse
      εI∍}     # Shorten both strings to a length equal to the input
          I∍   # Extend this list of strings to a length equal to the input
            »  # Join the strings by newlines (and output implicitly)

Answer 44

Oracle SQL, 84 bytes

SQL> select rpad(substr(rpad('_',n,'x_'),mod(level,2)+1),n,'_')from t connect by level<=n
  2  /

RPAD(SUBSTR(RPAD('_',N,'X_'),MOD(LEVEL,2)+1),N,'_')
--------------------------------------------------------------------------------
x_x_x_x_x_
_x_x_x_x_x
x_x_x_x_x_
_x_x_x_x_x
x_x_x_x_x_
_x_x_x_x_x
x_x_x_x_x_
_x_x_x_x_x
x_x_x_x_x_
_x_x_x_x_x

10 rows selected.

Answer 45

MUMPS (58 56 88 86 88 bytes)

Assuming you can execute this code in an interpreter:

(ANSI M)

  r v,! f i=1:1:v d  w !
  . f j=1:1:v w $s(i#2:$s(j#2=1:"X",1:" "),1:$s(j#2:" ",1:"X"))

We could bring this down to 82 bytes if we allow a new line at the beginning of the output:

 r v,! f i=1:1:v w ! f j=1:1:v w $s(i#2:$s(j#2=1:"X",1:" "),1:$s(j#2=1:" ",1:"X"))

Bonus

We can take advantage of the fact that M doesn't have any reserved keywords to give further headache:

s s=8 f f=1:1:s w ! f w=1:1:s w $s(f#2:$s(w#2=1:"X",1:" "),1:$s(w#2=1:" ",1:"X"))

Caché ObjectScript (a superset of ANSI M) (83 bytes):

r v,! f i=1:1:v{f j=1:1:v{w $s(i#2:$s(j#2=1:"X",1:" "),1:$s(j#2=1:" ",1:"X"))} w !}

Explanation:

both cases are essentially the same. Accept input "v" from user. While looping from 1 to v, execute an inner loop such that if i#2 isn't zero, write "X" if j#2 isn't zero and " " in all other cases (i.e. when j#2 is zero). if i#2 is zero, do the opposite. After completing the inner loop, start a new line.

dang, realized I forgot to alternate lines *added another version of ANSI M and an ObjectScript version

Answer 46

Stax, 6 bytes

òeφ→α♪

Run and debug it

Unpacked, ungolfed, and commented, it looks like this.

cK      map over the cartesian square of [1..n] * [1..n]
        implicitly output from each row on separate lines
  +     add the coordinates
  .X @  index into string "X "

Run this one

Answer 47

Jelly, 17 bytes

⁾X ẋs2UÐeẋ³ŒHḢƊ€Y

Try it online!

This almost certainly can be golfed further; 17 bytes seems like too many.

Explanation:

⁾X ẋs2UÐeẋ³ŒHḢƊ€Y    Example input: 3
⁾X ẋ                 Repeat the string "X " times the input: "X X X "
    s2               Split it into chunks of length 2: ["X ", "X ", "X "]
      UÐe            Upend (reverse) the even indexes: ["X ", " X", "X "]
              Ɗ€     Apply to each...
         ẋ³          ...repeat each chunk times the input...:  ["X X X ", " X X X", "X X X "]
           ŒH        ...approximately split it into halves...: [["X X", " X "], [" X ", "X X"], ["X X", " X "]]
             Ḣ       ...take the head (first item) of each: ["X X", " X ", "X X"]
              Y      Join with newlines
                     Implicit output

Answer 48

Haskell 89 74 charaters

main=do n<-readLn;mapM_(putStrLn.take n).take n.cycle$map cycle["X "," X"]

Answer 49

PHP, 88 80 78

for($x=0;$x++<$i=$argv[1];){for($y=0;$y++<$i;)echo($y+$x)%2?" ":"X";echo"\n";}