facebook.rb

relationships = []
File.foreach("./input.txt") do |line|
  items = line.split(" ")
  relationships << [items[6], items[7]]
end

connections = Hash.new {|k, v| k[v] = []}
relationships.each do |pair|
  connections[pair[0]] << pair[1]
end

pre_clusters = []
connections.keys.each do |key|
  key_cluster = [key]
  connections[key].each do |friend|
    key_cluster << friend if connections[friend].include?(key)
  end
  pre_clusters << key_cluster
end

# clusters = pre_clusters.collect {|sub| sub.sort}.uniq
i = 0
legit_clusters = []
while i < pre_clusters.size
  add = true
  j = 0
  while j < pre_clusters.size
    if i == j
      j += 1
      next
    end
    # binding.pry
    add = false if (pre_clusters[i] - pre_clusters[j]).empty?
    j += 1
  end
  legit_clusters << pre_clusters[i] if add
  i += 1
end