hack fallout terminals

fallout.rb

##
# Program to help you hack terminals in Fallout
#
# Usage:
#
# Run this program with a '/' separated list of possible words, and
# (once you've made a guess) another '/' separated list of words and
# scores where the word and score are separated by a ':'
#
# In this example, the words shown in my terminal were:
#
#  CASTE
#  LINES
#  ALTER
#  OFFER
#  KEEPS
#  HAVEN
#  SPEED
#  BASIC
#
# I hadn't made a guess yet, so I started by running this:
#
# ```
# $ ruby fallout.rb CASTE/LINES/ALTER/OFFER/KEEPS/HAVEN/SPEED/BASIC
# ["CASTE", "LINES", "ALTER", "OFFER", "KEEPS", "HAVEN", "SPEED", "BASIC"]
# 
# Next guess: "ALTER"       3 guesses remaining
# ```
#
# As instructed, I chose "ALTER", and the terminal said it scored 0, so
# I ran this:
#
# ```
# $ ruby fallout.rb CASTE/LINES/ALTER/OFFER/KEEPS/HAVEN/SPEED/BASIC ALTER:0
# ["CASTE", "KEEPS", "BASIC"]
# 
# Next guess: "BASIC"       1 guesses remaining
# ```
#
# Notice we skipped "2 guesses remaining": the estimate of 3 was in case
# ALTER scored 1.
#
# BASIC scored 2, so I ran this:
#
# ```
# $ ruby fallout.rb CASTE/LINES/ALTER/OFFER/KEEPS/HAVEN/SPEED/BASIC ALTER:0/BASIC:2
# ["CASTE"]
# 
# Final answer: CASTE
# ```
#
# The only choice left is "CASTE", and it is the correct answer!

def count w1, w2
  w1.chars.zip(w2.chars).count { |a,b| a == b }
end

def hack w, t
  t.inject(w - t.map(&:first)) { |c, (w1, s)|
    c.find_all { |w2|
      s.to_i == count(w1, w2)
    }
  }
end

def solve w, t, m
  dw = hack(w, t)
  return 0 unless dw.size > 1
  return 1 if dw.size == 2

  dw.map {|a|
    solve(w, t + [[a, m[a]]], m)
  }.max + 1
end

w, t = ARGV[0].split('/'), (ARGV[1] || '').split('/').map { |x| x.split(':') }
dw = hack(w, t)
p dw

if dw.size > 1
  hh = Hash.new { |h1, w1| h1[w1] = Hash.new { |h2, w2| h2[w2] = count(w1, w2) } }

  (maximum,), guess = dw.map { |w1|
    [dw.map { |w2|
      m = hh[w2]
      solve(w, t + [[w1, m[w1]]], m) + 1
    }.sort.reverse, w1]
  }.sort.first

  puts
  puts "Next guess: #{guess.inspect}       #{maximum} guesses remaining"
  puts
else
  puts
  puts "Final answer: #{dw.first}"
  puts
end