ACM Micro-Challenge 1

pizza.rb

require "test/unit"

# Write a function called numPizzas, that takes the number of people present,
# the number of slices in a pizza, and the time of day, and returns the
# number of pizzas to buy (as a whole integer).
#
# Spec:
#   Signature: int numPizzas(int numPeople, int slicesPerPizza, int time)
#   Time is an int on 24-hour clock (0-23), e.g. 8 = 8am, 14 = 2pm
#   Between 11am - 11pm: 2 slices per person, else 1
#
# Example:
#   numPizzas(7, 12, 10) ---> 7 people with 12 slices per pizza at 10am => 1 pizza
#
# Test cases:
#   numPizzas(10, 10, 1)  # => 1  (12am)
#   numPizzas(10, 10, 1)  # => 1  (1am)
#   numPizzas(7, 12, 10)  # => 1  (10am)
#   numPizzas(20, 10, 11) # => 4  (11am)
#   numPizzas(7, 12, 15)  # => 2  (3pm)
#   numPizzas(5, 10, 23)  # => 1  (11pm)


def numPizzas(numPeople, slicesPerPizza, time)
  total_slices = (time.between?(11, 22)) ? (numPeople * 2) : numPeople
  (total_slices / slicesPerPizza.to_f).ceil
end


class PizzaTest < Test::Unit::TestCase
  def test_between_12am_and_11am         # 1 slice per person
    assert_equal 2, numPizzas(10, 5, 0)  # 12am
    assert_equal 1, numPizzas(10, 10, 1) # 1am
    assert_equal 1, numPizzas(7, 12, 10) # 10am
  end

  def test_between_11am_and_11pm          # 2 slices per person
    assert_equal 4, numPizzas(20, 10, 11) # 11am
    assert_equal 2, numPizzas(7, 12, 15)  # 3pm
  end

  def test_after_11pm                    # 1 slice per person
    assert_equal 1, numPizzas(5, 10, 23) # 11pm
  end
end