#!/usr/bin/ruby1.8


l = []

seen = {}
done = {1 => nil}


n = -1
1000.times \
{
        n += 4

        seen[n] = l.size
        l << [n]
}

5000.times \
{
        i = -1
        l2 = l.map { |l1| [l1[-1], i += 1] }

        n2, i = l2.min
        puts([0, n2].join("\t"))

        n2 = (n2 % 2 == 0) ? n2 / 2 : n2 * 3 + 1
        if (done.member?(n2)) then
                l[i].each { |x| done[x] = nil; p(x) }
                l[i] = [n += 4]
        end

        if (!(j = seen[n2]).nil?)

                x = l[j][-1]
                l[j] |= l[i]
                l[j] << x
                l[i] = [n += 4]
                seen[n] = i
        else
                l[i] << n2
                seen[n2] = i
        end

}