Project Euler 31

problem31.rb

def solve
  coins = [1, 2, 5, 10, 20, 50, 100, 200]
  goal = 200
  ways = Array.new
  ways << 1
  200.times do
    ways << 0
  end
  coins.each do |coin|
    coin.upto(goal) do |x|
      ways[x] += ways[x-coin]
    end
  end
  return ways[goal]
end