Programming task solution that was asked by lunarlogic.io

lunarlogic_io.rb

# LUNARLOGIC.IO PROGRAMMING TASK

# Imagine we are organizing a Lunar dinner. 
# 30 people have confirmed that they will come.
# We will all be seating at five 6-person tables (A, B, C, D, E, respectively).
# There will be 3 courses. After each course we'll change our seats.
# We'd like every person to sit with as many different people as possible throughout the dinner.
# As a bonus you may think of future similar occasions where different number of people and tables may be available.

# Write a program that would assign 30 people to their seats (A1, A2, A3, etc., up to E6) during each course with that goal in mind.
# As a bonus you may think of future similar occasions where different number of people and tables may be available. 

require 'set'

class Person
  attr_accessor :id, :acquaintances
  @@id = 1

  def initialize
    @id = @@id
    @@id += 1

    @acquaintances = Set.new
  end

  def meet(object)
    case object
    when Person
      @acquaintances << object
    when Table
      object.compact.each do |person|
        @acquaintances << person
      end
    end
  end

  # Return number of people that a person already has met at a given table.
  # The lower the acquaintance_score is the better.
  # Which means the person has not met most of the people at a given table yet.
  def acquaintance_score(table)
    score = 0
    table.each do |person|
      score += 1 if @acquaintances.include? person
    end
    score
  end
end

class Table < Array
  attr_accessor :id, :history
  @@id = 1

  def initialize(num_seats)
    @id = @@id
    @@id += 1

    @num_seats = num_seats
    @index = 0
    @history = []
    super()
  end

  # Seat a person at the table.
  # The person sitting at a table meets all the people that
  # are already sitting at the table at that time.
  def seat(new_person)
    new_person.meet(self)
    self.each do |person|
      person.meet(new_person)
    end
    self[@index] = new_person
    @index += 1
  end

  # Return whether the table is full
  def full?
    self.size.eql? @num_seats
  end

  # Clear table for new seating plan for the next course
  def clear
    @history << self.clone
    @index = 0
    super
  end
end

def seating_plan(num_people, num_tables, num_seats, num_courses)
  people = num_people.times.map { Person.new }
  tables = num_tables.times.map { Table.new(num_seats) }

  num_courses.times do |course|
    # If it's the first course
    # we can seat people however we want
    if course.eql? 0
      people_dupp = people.clone
      tables.cycle(num_seats) do |table|
        table.seat people_dupp.shift
      end
    # Otherwise seat people depending on their acquaintance score
    else
      people.each do |person|
        free_tables = tables.select{ |t| not t.full? }
        scores = free_tables.map { |table| person.acquaintance_score(table) }
        best_table = scores.index(scores.min)
        free_tables[best_table].seat(person)
      end
    end
    tables.map(&:clear)
  end

  # Print seating plan
  num_courses.times do |course|
    puts "Course ##{course + 1} sitting plan"
    tables.each do |table|
      puts "\tTable ##{table.id} #{table.history[course].map { |person| person.id }}"
    end
  end

  # Calculate how many people each person will meet with
  acquaintance_map = {}
  people.each do |person|
    num_acquaintances = person.acquaintances.size
    acquaintance_map[num_acquaintances.to_s] ||= []
    acquaintance_map[num_acquaintances.to_s] << person.id
  end

  # Sort acquaintance_map in decreasing order
  acquaintance_map = acquaintance_map.sort_by { |k, v| k.to_i }.reverse.to_h

  # Print num of acquaintances to the screen
  puts "\n\nAcquaintances"
  acquaintance_map.each do |k, v|
    puts "\tThese people will meet #{k} people: #{v}"
  end
end

num_people = 30
num_tables = 5
num_courses = 3
num_seats = 6

seating_plan(num_people, num_tables, num_seats, num_courses)

# EXAMPLE OUTPUT of seating_plan
#
# Course #1 sitting plan
# 	Table #1 [1, 6, 11, 16, 21, 26]
# 	Table #2 [2, 7, 12, 17, 22, 27]
# 	Table #3 [3, 8, 13, 18, 23, 28]
# 	Table #4 [4, 9, 14, 19, 24, 29]
# 	Table #5 [5, 10, 15, 20, 25, 30]
# Course #2 sitting plan
# 	Table #1 [1, 2, 3, 4, 5, 26]
# 	Table #2 [6, 7, 8, 9, 10, 27]
# 	Table #3 [11, 12, 13, 14, 15, 28]
# 	Table #4 [16, 17, 18, 19, 20, 29]
# 	Table #5 [21, 22, 23, 24, 25, 30]
# Course #3 sitting plan
# 	Table #1 [1, 7, 10, 13, 19, 22]
# 	Table #2 [2, 6, 14, 15, 18, 23]
# 	Table #3 [3, 9, 11, 17, 20, 24]
# 	Table #4 [4, 8, 12, 16, 25, 26]
# 	Table #5 [5, 21, 27, 28, 29, 30]


# Acquaintances
# 	These people will meet 15 people: [2, 3, 6, 8, 11, 12]
# 	These people will meet 14 people: [1, 4, 5, 9, 10, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29]
# 	These people will meet 12 people: [7, 26, 30]