A script that finds unique word templates

puzzles.rb

words = File.open("./TWL06.txt").read.downcase.gsub("\r", "").split("\n")
words.select! {|w| w.length == 6}

# Approach:
# 1. Generate an index that maps 2-templates (like "_l___x") to words ("climax").
# 2. Find 2-templates that map to just one word.

def templates(word)
  "Finds all fifteen (6! / 4! * 2!) 2-templates for a given word."
  inds = []; (0..4).collect {|i| (i + 1..5).each {|j| inds << [i, j]}}
  ts = []
  inds.each do |ij|
    w = word.split('')
    ((0..5).to_a - ij).each { |x| w[x] = "_" }
    ts << w.join
  end
  return ts
end

# Step 1.
index = {}
words.each do |word|
  templates(word).each do |t|
    if index[t] then index[t] << word else index[t] = [word] end
  end
end

# Step 2.
p index.select {|k, v| v.length == 1}