apple_stock.rb

# Only keep track of the best

require "pp"
require "minitest/autorun"

class StockTest < Minitest::Test
  def pick_best_time_to_buy(stock)
    best = {value: 0}
    
    stock.each_with_index  do |buy_price, buy_index|
      stock.each_with_index do |sell_price, sell_index|
        next unless buy_index < sell_index

        value = sell_price - buy_price
        best = {sell_index: sell_index, buy_index: buy_index, value: value}  if best[:value] < value
      end
    end  
    
    best
  end
  
  def test_picking_best_time_to_buy
    stock = [1,8,3,0,1,54,29,1,3,10,49,10,39,28,41,1,3]

    max = pick_best_time_to_buy(stock)
        
    assert_equal 3, max[:buy_index]
    assert_equal 5, max[:sell_index]
    assert_equal 54, max[:value]
  end  
end