Pythagorean Triplets by Christian -- MKS Week 1

triplet.rb

require 'benchmark'

def triplet(perimeter)

	# Algorithm
	# Creates array of side pair [a,b] combinations
	# stores in array side_values
	# The largest side value tested is (perimeter/2)
	# since no triangle can be formed with anything
	# higher with fulfilling our conditions.
	# The smallest value tested is (perimeter/4)
	# (this was an approximation, from stats
		#gathered from testing up to perimeter = 10000)
	# iterates through the side_values
	# and checks for fulfilled conditions for
	# pythagorean triplet
	
	return false if perimeter <12

	triplets = []
	start_num = perimeter/4
	end_num = perimeter/2
	
	side_values = (start_num..end_num).to_a.combination(2).to_a
			  # - [[1,2],[1,3],[1,4]...]	

	side_values.each do |a,b|
		c =  Math.sqrt(a**2 + b**2)
		if is_integer(c) &&	a+b+c < perimeter
			triplets << [a,b,c.to_i]
		end
	end

	triplets_perimeter = triplets.map { |x| x.inject(&:+)}
	max_index = triplets_perimeter.each_with_index.max[1]
	max_triplet = triplets[max_index]

	return max_triplet

end

def is_integer(float_num)
	float_num.to_i == float_num
end

# puts triplet(10000).inspect
# puts Benchmark.measure {triplet(10000) }

Try this with the number 30. It should return 5, 12, 13