Euler Project Problem #015

euler15.rb

# Solution to Project Euler's fifteenth problem
# http://projecteuler.net/index.php?section=problems&id=15
# How many routes are there through a 2020 grid?
def generate_Pascals_triangle(depth)
	triangle = [[1], [1,1]]
	(2..depth).each do |d|
		# generate row #
		triangle[d] = []
		next_row = triangle[d-1]
		next_row.push 0; next_row.unshift 0
		(1..(next_row.length-1)).each do |o|
			triangle[d].push (next_row[o-1] + next_row[o])
		end
	end
	return triangle
end
number = 40
triangle = generate_Pascals_triangle(number)
p triangle[40][20]