popular_toppings.rb

require 'httparty'
require 'json'

=begin
Using any modern language, write a throw-away app or script that will download orders directly from http://files.olo.com/pizzas.json and output the top 20 most frequently ordered pizza topping combinations. List the toppings for each popular pizza topping combination along with its rank and the number of times that combination has been ordered.
=end

res = HTTParty.get('http://files.olo.com/pizzas.json')
data = JSON.parse(res)

def tally_data(data)
  tally = Hash.new
  data.each do |record|
    toppings = record['toppings']
    toppings.each do |tp|
      unless tally.has_key? tp
        tally.store(tp, 1)
      else
        new_total = tally[tp] + 1 
        tally.store(tp, new_total)
      end
    end
  end
  return tally
end

def rank_toppings(hash)
  rankings = Array.new
  hash.each_pair do |topping, orders|
    if rankings.length == 0
      rankings << [topping, orders]
    else
      rankings.each_with_index do |record, ii|
        if record.last < orders
          rankings.insert(ii, [topping, orders])
          break
        elsif ii + 1 == rankings.length
          rankings << [topping, orders] 
          break
        end
      end
    end
  end
  return rankings
end

result =  rank_toppings(tally_data(data))[0..19]

puts 
result.each_with_index {|record,ii| puts "#{record.first} | rank: #{ii + 1} | orders: #{record.last} "}