Secret Meetings

secret_meetings.rb

# /*
# There are N people
# Some subset of the N people know the secret
# There are M meetings which are encoded as subsets of the N people
# There is a total order over the meetings that tells you the order in which they occur
# When people meet they share the secret

# Calculate the set of people who know the secret after all the meetings
# */

initial_set = [1,2]
meetings = [
  [6],
  [1,2,3],
  [3,4],
  [5]
]

def people_who_know_secret(initial_set, meetings)
  people_that_know_secret = initial_set
  for meeting in meetings
    if !people_that_know_secret.intersection(meeting).empty?
      people_that_know_secret = (people_that_know_secret + meeting).uniq
    end
  end
  people_that_know_secret
end

people_that_know_the_secret = people_who_know_secret(initial_set, meetings)

puts people_that_know_the_secret # [1,2,3,4]