drain.rb

def len01(ns)
	nl = ns.length
	l1 = ns.split(/0+/).map { |x| x.length }
	
	l2 = ns.split(/1+/)[1..-1]
	l2 = [''] if (l2.nil?)
	
	l0 = l2.map { |x| x.length }
	return l0, l1
end

def mx01(ns)
	l0, l1 = len01(ns)
	return l1.max, l0.max
end

def d(s)
        c = s.split('').select { |x| x == '1' }.size
	d = c.to_f / s.length
        return d
        
end


def add(l, n, x)

	return if (n == 1 && !x['mxr'].nil?)

	p = x['p'] + (n % 2).to_s
	mxp = mx01(p).max
	return if (mxp > 20)

	ns = n.to_s(2)
	mxr = mx01(ns)[0]

	mxr = {'mxr' => mxr, 'l1i' => x['l1'].size}

	l << {'n' => n, 
		'l1' => x['l1'] + [n], 
		'p' => p, 
		'd' => (d(ns) - 0.5).abs,
		'mxp' => mxp, 
		'mxr' => [x['mxr'], mxr].compact.max_by { |x| x['mxr'] }}

end




l = []
add(l, 1, {'l1' => [], 'p' => '', 'mxr' => nil})


50000.times \
{
	|t|
	
	l = l.sort_by { |x| [x['mxr']['mxr'], x['l1'].size, x['d']] }.reverse
	x = l.delete_at(rand([l.size, 100].min))
	l.pop if (l.size > 2000)
	
	p({'t' => t, 'ls' => l.size}
		.merge(x['mxr'])
		.merge({'d' => x['d'], 'l1s' => x['l1'].size})) if (t % 100 == 0)
	
	n = x['n']
	
	
	add(l, (n - 1) / 3, x) if ((n - 1) % 3 == 0 && ((n - 1) / 3).odd?)
	add(l, n * 2, x)

}