Check whether a string contains all the characters of another string in Ruby

Question

Let's say I have a string, like string= "aasmflathesorcerersnstonedksaottersapldrrysaahf". If you haven't noticed, you can find the phrase "harry potter and the sorcerers stone" in there (minus the space).

I need to check whether string contains all the elements of the string.

string.include? ("sorcerer") #=> true
string.include? ("harrypotterandtheasorcerersstone") #=> false, even though it contains all the letters to spell harrypotterandthesorcerersstone

Include does not work on shuffled string.

How can I check if a string contains all the elements of another string?

Answer 1

Sets and array intersection don't account for repeated chars, but a histogram / frequency counter does:

require 'facets'

s1 = "aasmflathesorcerersnstonedksaottersapldrrysaahf"
s2 = "harrypotterandtheasorcerersstone"
freq1 = s1.chars.frequency
freq2 = s2.chars.frequency
freq2.all? { |char2, count2| freq1[char2] >= count2 } 
#=> true

Write your own Array#frequency if you don't want to the facets dependency.

class Array
  def frequency
    Hash.new(0).tap { |counts| each { |v| counts[v] += 1 } }
  end
end