ransom_note.rb

# frozen_string_literal: true

# Ransom Note
# Given an arbitrary ransom note string and another string containing letters from all the magazines,
# write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false.

# Each letter in the magazine string can only be used once in your ransom note.

# Note:
# You may assume that both strings contain only lowercase letters.

# canConstruct("a", "b") -> false
# canConstruct("aa", "ab") -> false
# canConstruct("aa", "aab") -> true

# @param {String} ransom_note
# @param {String} magazine
# @return {Boolean}
def can_construct(ransom_note, magazine)
  available_letters = {}
  magazine.chars.each do |ch|
    available_letters[ch] = available_letters[ch].to_i + 1
  end

  ransom_note.chars.each do |ch|
    return false if available_letters[ch].to_i.zero?

    available_letters[ch] = available_letters[ch].to_i - 1
  end
  true
end