gistfile1.rb

NWORDS = Hash.new( 1 )

File.new('holmes.txt').read.downcase.scan(/[a-z]+/) { |k| NWORDS[k] += 1 }

LETTERS = ("a".."z").to_a.join

def edits1 word
  n = word.length
  alteration = insertion = []
  
  deletion = (0...n).collect { |i| word[0...i] + word[i + 1..-1] }                                          # Deletion
  transposition = (0...n-1).collect { |i| word[0...i] + word[i + 1, 1] + word[i, 1] + word[i + 2..-1] }     # Transposition
  n.times { |i| LETTERS.each_byte { |l| alteration << word[0...i] + l.chr + word[i + 1..-1] } }             # Alterations
  ( n + 1 ).times { |i| LETTERS.each_byte { |l| insertion << word[0...i] + l.chr + word[i..-1] } }          # Insertion
  
  if ! ( result = deletion + transposition + alteration + insertion ).empty? then result end
end

def known_edits2 word
    edits1( word ).collect { |e1| edits1( e1 ).select { |e2| NWORDS.has_key?(e2) } }.reject { |v| v.empty?  }
end

def known words
    if ! ( result = words.select { |w| NWORDS.has_key?(w) } ).empty? then result end
end

def correct word
  (known([word]) or known(edits1(word)) or known_edits2(word) or [word]).max { |a,b| NWORDS[a] <=> NWORDS[b] }.first
end