Simulate rotating a board

Question

Introduction

You're playing a matching game, in which coins are inserted at the top and fall to the bottom (onto the top coin) due to gravity.

So this

O <- inserting this coin

OO O
OOOOO

will become this

O
OO O
OOOOO

Now imagine someone rotates the board clockwise. The following will happen:

1. The board is rotated

OOO
OO
O
OO
O

2. Coins fall down due to gravity

O
O
OO
OO
OOO

Your task

Your task is to simulate the rotation of the board by writing a program or a function. For the sake of simplicity we're only dealing with one kind of coin (it's not a too exciting matching game, is it…). You can assume that gravity is applied only after the rotation is complete. The board is rotated clockwise.

Input

The input is going to be a string, which contains 3 types of characters:

• O (capital o) OR 0 (zero) - a coin (you decide which one your solution supports)
• (space) - an empty field
• \n (new line) - end of row

The input represents the state of the board. You can assume, the input is well formed and contains a valid state of the board (no coins are floating). The input can be a function parameter, or can be read from the standard input or from a file.

Output

The output is the new state of the board after rotation. The output contains the same 3 types of characters as the input. The output can be returned from your function or can be written to the standard output or to a file.

Sample

Input1:

O
OO O
OOOOO

Output1:

O
O
OO
OO
OOO

Input2:

O O
O O

Output2:

OO
OO

You can use any language and the standard library of the chosen language. Shortest program in bytes wins.

Answer 1

GolfScript, 14 12 characters

' '-n%zip$n*

Input must be given on STDIN, the character for coins can be any non-whitespace characters. Try here. Thanks to Peter for pointing out a two character reduction.

Answer 2

Ruby 2.0, 59 characters

puts$<.map(&:chars).reverse.transpose.sort[1,50].map &:join

Input via stdin, assumes lines all have the same length. This is probably much longer than necessary. But at least it's readable ...

Answer 3

Javascript (E6) 103

First try, just matrix operations. Each row in input string need to be padded.
Quite wordy.

R=t=>(x=t.split('\n').reverse().map(x=>[...x].sort()),x.map((c,i)=>x.map(r=>r[i]).join('')).join('\n'))

Pseudo code

1. string -> array of rows
2. up/down reverse array
3. each row -> char array
4. sort each row (coins 'fall' to right)
5. transpose
6. each char array in a row -> a string
7. join array -> single string

Answer 4

J - 49 31 24 bytes

I think there might be unnecessary rotations in there, but otherwise it works fine. It's a function that takes the input as specified, coins being O. No trailing whitespace is required in the input.

New version, inspired by edc65's Javascript answer:

f=:[:|."1@|:[:/:~"1,;._2

Explanation:

f=:[:|."1@|:[:/:~"1,;._2
                   ,;._2 Split the string at every fret, which is the last character in the string (newline).
              /:~"1      Sort every row separately.
     |."1@|:             Rotate the array clockwise.

---

Old version:

f=:[:|:((#~=&' '),=&'O'#])"1@|:@(|."1@|:)@(,;._2)

Explanation:

f=:[:|:((#~=&' '),=&'O'#])"1@|:@(|."1@|:)@(,;._2)
                                          (,;._2) Split the string at every fret, which is the last character in the string (newline).
                                (|."1@|:)@        Rotate the array clockwise.
                             |:@                  Reverse the axes (columns become rows and vice-versa).
       ((#~=&' '),=&'O'#])"1                      Function that applies the "gravity"
                          "1                       Apply to every row separately:
                  =&'O'#]                           Get the O's in the row.
       (#~=&' ')                                    Get the spaces in the row.
                ,                                   Join them, spaces come first.
  [:|:                                            Reverse axes again.

---

Examples (note that multiline strings start with 0 : 0 and end withh a bracket):

   f 0 : 0
O
OO O
OOOOO
) NB. output starts now
O  
O  
OO 
OO 
OOO
   f 0 : 0
O O
O O
) NB. Output starts now.

OO
OO

Answer 5

Python 2 (69) (79)

for c in sorted(zip(*raw_input().split("\\n"))):print''.join(c[::-1])

Takes input padded with spaces so all lines have equal length. The split creates an arrat of each line. The zip effectively transposes the array. Then, the sorted sorts tuples in lexicographic order, causing all coins to fall to the bottom. Finally, we print each line, turning it back into a string, though we must reverse it first. Doing print'O'*c.count('O') is equivalent and uses the same number of characters.

Example run:

>> O    \nOO O \nOOOOO
O
O
OO
OO
OOO

Answer 6

Haskell — 86

Just learning, so I'm sure this can be improved.

import Data.List
c=putStr.unlines.filter(/="").sort.map(filter(/=' ')).transpose.lines

Sample Input:

let a = "O    \nOO O \nOOOOO"
let b = " O O \n O O "
c a
c b

Sample Output:

O
O
OO
OO
OOO

OO
OO

Answer 7

C, 167 119 bytes

This shorter version is (unfortunately?) much clearer than the original too.

m;j;b[99];r;main(){while(j=getchar()+1)j-11?m+=j-33&&++b[r]>m:++r;for(j=r;m+1;putchar(j--?m<b[j]?79:32:(j=r,m--,10)));}

Answer 8

Racket: 130

(let l((a'()))(let((b(sort(string->list(read-line))char<?)))(if
(null? b)(apply map(λ x(map display x)(newline))a)(l(cons b a)))))

It requires you pad with spaces so the lines are equal lemgth.

Answer 9

C# - 209 174 bytes

Right, I have to try this Code golf at some point I reckon. Created a function (r) that rotates the board and prints it. I guess I'm cheating a little when I am printing my char array, but if you cannot figure out why you shouldn't be mad :)

Thanks to ProgramFOX for the tips :)

void r(string s){int x=s.IndexOf('\n'),j,i=-1,k,z=x+1;var y=new char[x*x+x];for(;++i<x;y[z*(i+1)-1]='\n')for(k=j=x;j>0;)if(s[i*z+--j]=='0')y[k--*z-i-2]='0';Console.Write(y);}

Cheat

new char[x*x+x] fills the array with '\0' and not ' '