第30回オフラインリアルタイムどう書く「とある世界のタクシー料金」の ruby による実装

DISTS=->(){
  raw="AB1090e  AC180e  AD540r  BC960e  BG1270e  CD400r  CF200e  DE720r  DF510r  EG1050r  FG230r"
  raw.scan( /([A-Z]{2})(\d+)([er])/ ).each.with_object({}){ |(path, dist, city),o|
    o[path]=[dist.to_i, city.to_sym].freeze
  }
}.().freeze

def solve_impl( paths, dist, cost )
  return cost if paths.empty?
  curpos=paths[0]
  if curpos[0]<dist
    solve_impl( paths.drop(1), dist-curpos[0], cost )
  else
    solve_impl( paths, 200+dist, cost+{e:60, r:50}[curpos[1]] )
  end
end

def solve( src )
  paths=src.chars.each_cons(2).map{ |a,b|
    DISTS[a+b] || DISTS[b+a]
  }
  start =  "ABC".include?(src[0]) ? [995,400] : [845,350]
  solve_impl( paths, *start ).to_s
end

DATA.each.map do |line|
  ix, src, expected = line.split(/\s+/)
  next unless src
  actual = solve( src )
  ok = actual==expected
  puts [ ok ? nil : "**NG**", ix, src, actual, ok ? nil : expected ].compact.join("  ")
  ok
end.all?.tap{ |all_ok|
  puts "Everything is Okay!" if all_ok
}
__END__
0 ADFC  510
1 CFDA  500