灯りと鏡 (Ruby)

無限に続く場合があるのが若干面倒でした.

tyama_henae27pre.rb

#!/usr/bin/ruby
#http://nabetani.sakura.ne.jp/hena/orde27ligmir/
#https://qiita.com/Nabetani/items/0b2f459ec128c89948f4

#x,y
D={
    '.'=>{
        [0,-1]=>[0,-1],  #N
        [1,0]=>[1,0],   #E
        [0,1]=>[0,1],   #S
        [-1,0]=>[-1,0], #W
    },
    '1'=>{
        [0,-1]=>[1,0],  
        [1,0]=>[0,-1],
        [0,1]=>[-1,0],
        [-1,0]=>[0,1],
    },
    '0'=>{
        [0,-1]=>[-1,0],  
        [1,0]=>[0,1],
        [0,1]=>[1,0],
        [-1,0]=>[0,-1],
    },
}
H=W=5

while gets
    m=$_.chomp.split('/')
    x,y=[0,0]
    H.times{|h|W.times{|w|
        if m[h][w]=='Y'
            x,y=w,h
            m[h][w]='.'
        end
    }}
    r=[]
    dx,dy=[0,-1]
    visited={[x,y,dx,dy]=>1}
    while 0<=x&&x<W && 0<=y&&y<H && m[y][x]!='x'
        r<<[x,y]
        dx,dy=D[m[y][x]][[dx,dy]]
        x+=dx
        y+=dy
        k=[x,y,dx,dy]
        break if visited[k]
        visited[k]=1
    end
    puts r.map{|x,y|(x+y*W+97).chr}.uniq.sort*''
    STDOUT.flush
end