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require "spec_helper"
describe "problem nine" do
# A Pythagorean triplet is a set of three natural numbers, a < b < c, for which, a^2 + b^2 = c^2
# For example, 3^2 + 4^2 = 9 + 16 = 25 = 5^2.
# There exists exactly one Pythagorean triplet for which a + b + c = 1000.
# Find the product abc.
#
class PythagoreanTriplet
include Enumerable
def initialize(max = 100_000)
@max = max
end
def each(&block)
triplets.each(&block)
end
private
def triplets
Enumerator.new do |yielder|
0.upto(@max) do |n|
x = n * n
y = (n+1) * (n+1)
z = (n+2) * (n+2)
if x + y == z
puts "#{n}: MATCH"
yielder.yield([n, n+1, n+2])
else
puts "#{n}: no match"
end
end
end
end
end
subject { PythagoreanTriplet.new }
it "returns the triplet for 25" do
expect(subject.first).to eql([3, 4, 5])
result = subject.find do |triplet|
(triplet.last * triplet.last) == 25
end
expect(result).to eql([3, 4, 5])
end
it "returns the triplet for 1000" do
result = subject.find do |triplet|
(triplet.last * triplet.last) == 1_000
end
expect(result).to eql(10)
end
end
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