graphs.rb

require 'pry'
g = [[1, 2],
     [1, 4],
     [2, 1],
     [2, 3],
     [2, 5],
     [3, 2],
     [3, 11],
     [4, 1],
     [4, 5],
     [4, 7],
     [5, 2],
     [5, 4],
     [5, 6],
     [5, 8],
     [6, 5],
     [6, 9],
     [6, 10],
     [7, 4],
     [7, 13],
     [8, 5],
     [8, 14],
     [9, 6],
     [9, 12],
     [10, 6],
     [10, 11],
     [11, 3],
     [11, 10],
     [12, 9],
     [13, 7],
     [13, 14],
     [14, 8],
     [14, 13],
     [90, 91],
     [91, 90]]


# giant = File.open("/Users/jeff/code/jobs/graphs/connections.txt", "rb").readlines
# giant.collect! do |line|
#   line = line.split
# end

def grapher(array)
  hash = Hash.new { |hash, key| hash[key] = [] }
  array.each do |pair|
    hash[pair[0]] ||= []
    hash[pair[0]] << pair[1]
  end
  hash
end


# p grapher(giant)
# p grapher(g)



def accessible?(origin, destination, graph, exclude = [])

  paths = graph[origin] - exclude
  exclude << origin

  if graph[origin].include?(destination)
    true
  elsif paths.empty?
    false
  else
    paths.each do |e|
      return true if accessible?(e, destination, graph, exclude)
    end
    false
  end

end


test = [[1,3], [1,2]]


graph = grapher(test)
graph = grapher(g)

p graph

p accessible?(1, 2, graph)
p accessible?(1, 3, graph)
p accessible?(2, 90, graph)

# binding.pry