change.rb

require 'rspec'

# input: integer (0-100)
# output: hash, e.g.
#             5 -> {quarters: 0, dimes: 0, nickels: 1, pennies: 0}
#             12 -> {quarters: 0, dimes: 1, nickels: 0, pennies: 2}

describe "#make_change" do
  it "1 should return 1 penny" do
    expect(make_change(1)).to eq(quarters: 0, dimes: 0, nickels: 0, pennies: 1)
  end

  it "4 should return 4 pennies" do
    expect(make_change(4)).to eq(quarters: 0, dimes: 0, nickels: 0, pennies: 4)
  end

  it "5 should return 1 nickel" do
    expect(make_change(5)).to eq(quarters: 0, dimes: 0, nickels: 1, pennies: 0)
  end

  it "7 should return 1 nickel and 2 pennies" do
    expect(make_change(7)).to eq(quarters: 0, dimes: 0, nickels: 1, pennies: 2)
  end

  it "10 should return 1 dime" do
    expect(make_change(10)).to eq(quarters: 0, dimes: 1, nickels: 0, pennies: 0)
  end

  it "25 should return 1 quarter" do
    expect(make_change(25)).to eq(quarters: 1, dimes: 0, nickels: 0, pennies: 0)
  end
end

describe "#coin_count" do
  it "it returns cents divided by coin_value and the remainder" do
    expect(coin_count(76, 25)).to eq([3,1])
  end
end

QUARTER = 25
DIME = 10
NICKEL = 5

def coin_count(cents, coin_value)
  [cents / coin_value, cents % coin_value]
end

def make_change(cents)
  quarters, remaining_cents = coin_count(cents, QUARTER)
  dimes, remaining_cents = coin_count(remaining_cents, DIME)
  nickels, remaining_cents = coin_count(remaining_cents, NICKEL)
  pennies = remaining_cents

  {quarters: coin_count(QUARTER), dimes: dimes, nickels: nickels, pennies: pennies}
end