くねくね増加列

#!/usr/bin/env ruby
#http://qiita.com/Nabetani/items/7ba11167ea28c929fcf2
#http://nabetani.sakura.ne.jp/hena/ord23snakemoinc/
class Hena23
    def initialize(a)
        @a=a
        @memo={}
    end
    def dfs(x,y,nprev)
        return 0 if x<0||@a[0].size<=x || y<0||@a.size<=y || @a[y][x]<=nprev
        return @memo[[x,y]]||=[[-1,0],[1,0],[0,-1],[0,1]].map{|_x,_y|
            dfs(x+_x,y+_y,@a[y][x])+1
        }.max
    end
    def run
        @a.size.times.lazy.map{|y|
            @a[0].size.times.lazy.map{|x|
                dfs(x,y,-1)
            }.max
        }.max
    end
end

if $0==__FILE__
    STDOUT.sync=true
    while gets
        p Hena23.new($_.chomp.split('/').map{|e|e.split('').map(&:to_i)}).run
    end
end