match.rb

#! /usr/bin/ruby
# This program takes a list of users, their desires, and their possessions.
# Then it asks for a particular user and matches them with the best user
# for their desires.

class User
  attr_reader :has, :wants
  attr_accessor :score
  def initialize (has=[], wants=[])
    @score = 0
    @has = has
    @wants = wants
  end
end

users = []
user1 = User.new(has=["A", "C"], wants=["B", "D"])
users << user1
user2 = User.new(has=["D"], wants=["A"])
users << user2
user3 = User.new(has=["A", "B", "D"], wants="C")
users << user3

def find_best(users=users, user=user1)
  best = user
  users.each do |u|
    user.wants.each { |w| u.score += 1 if u.has.include? w }

    best = u if u.score > best.score
    break if u.score == user.wants.length
  end
  best
end

p find_best(users = users, user = user1)