Hi,
here is my solution (00111_gizmo.rb)
Karl
···
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require 'stringio'
class SecretAgent00111CommunicationGizmo
class UndefinedRLE < StandardError
end
private
class Rle
def initialize
@data = []
@count = 0
end
def <<(event)
if event
@count += 1
else
@data << @count
@count = 0
end
end
def get
@count == 0 ? @data : nil
end
end
class UnRle
def initialize
@data = []
end
attr_reader :data
def <<(count)
count.times { @data << true }
@data << false
end
end
public
class Encoder < Rle
def initialize(exponent, output)
super()
@output = output
@exponent = exponent
@byte = 0
@byte_bit = 0x80
insert @exponent, 8
end
def <<(event)
super(event)
while count = @data.shift
(count >> @exponent).times { insert 1 }
insert 0
insert count, @exponent
end
end
def finish
self << false
insert 1 while @byte_bit != 0x80
end
private
def insert(num, bits = 1)
(bits-1).downto(0) do |n|
@byte |= @byte_bit if num[n] == 1
if (@byte_bit >>= 1) == 0
@output.putc @byte
@byte_bit = 0x80
@byte = 0
end
end
end
end
class Decoder < UnRle
def initialize(input)
super()
@exponent = 0
@input = input
@count = 0
@remainder_bit = 0
end
def exponent
decode
@exponent
end
def read
decode
data = @data
@data = []
data
end
private
def decode
while byte = @input.getc
if @exponent == 0
@exponent = byte
else
insert byte
end
end
end
def insert(byte)
7.downto(0) do |n|
if @remainder_bit == 0
if byte[n] == 1
@count += 1 << @exponent
else
@remainder_bit = 1 << (@exponent - 1)
end
else
@count += @remainder_bit if byte[n] == 1
if (@remainder_bit >>= 1) == 0
self.<<(@count)
@count = 0
end
end
end
end
end
def SecretAgent00111CommunicationGizmo.rle(arr)
rle = Rle.new
arr.each do |event|
rle << event
end
out = rle.get
raise UndefinedRLE, "undefined rle" unless out and not out.empty?
out
end
def SecretAgent00111CommunicationGizmo.unrle(arr)
unrle = UnRle.new
arr.each do |count|
unrle << count
end
unrle.data
end
def SecretAgent00111CommunicationGizmo.encode(arr, exp)
io = StringIO.new
encoder = Encoder.new(exp, io)
arr.each do |event|
encoder << event
end
encoder.finish
io.string
end
def SecretAgent00111CommunicationGizmo.decode(bits)
io = StringIO.new(bits)
decoder = Decoder.new(io)
arr = decoder.read
arr.pop if arr.last == false
arr
end
end