run2.rb

#!/usr/bin/ruby1.8
 
 
 
 
def f(n)
 
        n2 = n
        s = ''
        while (n >= n2)
 
                p = n % 2
                n = (p == 0) ? n / 2 : (n * 3 + 1) / 2
                s << p.to_s
 
        end
        return s
 
end
 
def match(s, l1, l2)
 
        j = 0
        j += 1 while (j < s.length && s[j, 1] == '0')
        return [j, 0, s[0...j], s[j..-1]] if (j > 0) 
 
        m = [0, nil, '', s]
        l1.each_with_index \
        {
                |s2, i|
                j = 0
                j += 1 while (j < s.length && j < s2.length && s[j, 1] == s2[j, 1])
                m = [j, l2[i], s[0...j], s[j..-1]] if (j > m[0])
        }
 
        return m
 
end
 
 
n = 3
l1 = []
l2 = []
m = 0
i = 0
loop \
{
	s0 = s = f(n)
 
        l = []
        l3 = []
        while (s != '')
                j, x, s1, s2 = match(s, l1, l2)
                if (s1 == '') then
                        l << s2
                        l3 << -1
                        break 
                end
                l << s1
                l3 << x
                s = s2
        end
	z = l3.select { |x| x != 0}.size
	m = z if (z > m)

	if (i % 100 == 0) then
		puts([n, l3[0], m].join("\t"))
		m = 0
		$stdout.flush
	end
 
#       p([n, s0, l3, l])
        raise if (l.join != s0)
 
        l1 << s0
        l2 << n
        n += 4
	i += 1
}