complex sporcle-like word puzzles

sporcle.rb

N = 6
R = 2

def masks
  @masks ||= (0..N - 1).to_a.combination(N - R).to_a
end

def templates(word)
  masks.inject([]) do |templates, indexes_to_hide|
    arr = word.split('')
    indexes_to_hide.each { |i| arr[i] = "_" }
    templates << arr.join("")
  end
end
 
words = File.open('./TWL06.txt').readlines.map(&:chomp).select { |w| w.length == N }

index = words.inject(Hash.new(0)) do |idx, word|
  templates(word).each { |t| idx[t] += 1 }
  idx
end

puts index.select { |_, v| v == 1 }.map(&:first)

Compare the method of generating all of the (6c2 * 26² = 10,140) templates first. There, for every template you'd have to check all of the words. Here you're only doing 15 ops per word.