Димитър обнови решението на 23.10.2015 23:06 (преди над 8 години)
+class Integer
+ def prime?
+ return false if self == 1
+
+ root = Math.sqrt(self)
+ divisor = 2
+
+ while divisor <= root
+ return false if self % divisor == 0
+ divisor += 1
+ end
+
+ true
+ end
+end
+
+class RationalSequence
+ include Enumerable
+
+ def initialize(limit)
+ @limit = limit
+ end
+
+ def each
+ current = Rational(1)
+ direction = DIRECTIONS[:down]
+ counter = 0
+
+ while counter < @limit
+ yield current
+
+ current = calculate_next(current, direction)
+ direction = change_direction(current, direction)
+ counter += 1
+ end
+ end
+
+ private
+
+ DIRECTIONS = {down: [1, 0], right: [0, 1], down_left: [1, -1], up_right: [-1, 1]}
+
+ def reducible?(numerator, denominator)
+ numerator.gcd(denominator) != 1
+ end
+
+ def calculate_next_irreducible(numerator, denominator, direction)
+ if reducible?(numerator, denominator)
+ calculate_next_irreducible(numerator + direction[0], denominator + direction[1], direction)
+ else
+ Rational(numerator, denominator)
+ end
+ end
+
+ def calculate_next(current, direction)
+ numerator = current.numerator + direction[0]
+ denominator = current.denominator + direction[1]
+
+ calculate_next_irreducible(numerator, denominator, direction)
+ end
+
+ def change_direction(current, direction)
+ case
+ when direction == DIRECTIONS[:down] then DIRECTIONS[:up_right]
+ when direction == DIRECTIONS[:right] then DIRECTIONS[:down_left]
+ when (direction == DIRECTIONS[:down_left] and current.denominator == 1) then DIRECTIONS[:down]
+ when (direction == DIRECTIONS[:up_right] and current.numerator == 1) then DIRECTIONS[:right]
+ else direction
+ end
+ end
+end
+
+class PrimeSequence
+ include Enumerable
+
+ def initialize(limit)
+ @limit = limit
+ end
+
+ def each
+ current = 2
+ counter = 0
+
+ while counter < @limit
+ if current.prime?
+ yield current
+ counter += 1
+ end
+
+ current += 1
+ end
+ end
+end
+
+class FibonacciSequence
+ include Enumerable
+
+ def initialize(limit, first: 1, second: 1)
+ @limit = limit
+ @first = first
+ @second = second
+ end
+
+ def each
+ current_number, next_number = @first, @second
+ counter = 0
+
+ while counter < @limit
+ yield current_number
+
+ current_number, next_number = next_number, current_number + next_number
+ counter += 1
+ end
+ end
+end
+
+module DrunkenMathematician
+ module_function
+
+ def meaningless(n)
+ groups = RationalSequence.new(n).partition do |rational|
+ rational.numerator.prime? or rational.denominator.prime?
+ end
+
+ groups[0].reduce(1, :*) / groups[1].reduce(1, :*)
+ end
+
+ def aimless(n)
+ pairs = PrimeSequence.new(n).each_slice(2).to_a
+ pairs.last << 1 if n.odd?
+
+ rationals = pairs.map { |pair| Rational(pair[0], pair[1]) }
+ rationals.reduce(0, :+)
+ end
+
+ def worthless(n)
+ return [] if n == 0
+
+ fibonacci_number = FibonacciSequence.new(n).to_a.last
+
+ cut_size = 1
+ rationals_cut = RationalSequence.new(cut_size)
+ while rationals_cut.reduce(:+) <= fibonacci_number
+ cut_size += 1
+ rationals_cut = RationalSequence.new(cut_size)
+ end
+
+ RationalSequence.new(cut_size - 1).to_a
+ end
+end