A Ruby program which checks if two strings are anagrams of each other using two methods: sorting and frequency counting

anagram.rb

#!/usr/bin/env ruby
# anagram.rb

module Anagram
    ASCII_COUNT = 256

    def sort
        self.chars.sort.join
    end

    # worst case O(n^2)
    def anagram?(other)
        return false if self.length != other.length

        self.sort == other.sort
    end

    # O(n)
    def anagram2?(other)
        return false if self.length != other.length

        histogram = Array.new ASCII_COUNT, 0
        
        self.length.times do |i|
            histogram[[i].ord] += 1
            histogram[other[i].ord] -= 1
        end

        histogram.any? { |count| count != 0 }
    end
end

class String
    include Anagram
end

if __FILE__ == $0
    filename = ARGV[0]

    lines = IO.readlines(filename).map &:chomp

    puts %Q{Sorting: "#{lines[0]}" and "#{lines[1]}" are #{ lines[0].anagram?(lines[1]) ? '' : 'not' } anagrams}
    puts %Q{Histogram: "#{lines[0]}" and "#{lines[1]}" are #{ lines[0].anagram?(lines[1]) ? '' : 'not' } anagrams}
end

anagrams.txt

ipod lover
poor devil

call

ruby anagram.rb anagrams.txt