Voracious fish problem ruby using stack

voracious_fish.rb

class Fish
    def solution(weights, direction)
        stack = []
        survivor_count = 0

        weights.each_with_index do |elem, idx|
            if direction[idx] == 1
                stack.push(elem)
            else
                if stack.empty?
                    survivor_count += 1 
                    next
                end

                last = stack.pop
                if last > elem
                    stack.push(last)
                end
            end
        end

        survivor_count + stack.length
    end
end



puts Fish.new.solution([10, 8, 2, 6, 7], [1, 0, 0, 0, 0])