pad2b.rb

#!/usr/bin/ruby1.8



def f(n)
        s = ''
        while (n != 1)
                s << (n % 2).to_s
                n = (n % 2 == 0) ? n / 2 : n * 3 + 1
        end
        return s
end


def adj(l2)

        l3 = l2.dup

        t = (l3.size + 1) / 2
        z = ((t == 0) ? 0 : rand(t)) * 2
        l = (0..10).to_a
        r0 = l3[z].length
        l.delete_at(r0)

        r = l.delete_at(rand(l.size))
        l3[z] = '0' * r

#       p([t, z, l3])

        s = l3.join('')

        n = 1
        while (s != '')

                if (s[0, 1] == '0') then
                        n <<= 1
                else
                        break if (n % 3 != 1 || ((n - 1) / 3) % 2 == 0)
                        n = (n - 1) / 3
                end
                s[0, 1] = ''
        end
        j = ((l3.size - 1) - z) / 2

        return s == '', j, r0, r
end

def seq(n)


        s = f(n)
        s0 = s.dup

        l = []
        s1 = ''
        while (s != '')
                if (s1 == '' || s[0, 1] == s1[0, 1])
                        s1 << s[0, 1] 
                else
                        l << s1
                        s1 = s[0, 1]
                end
                s[0, 1] = ''
        end
        l << s1 if (s1 != '')

        return if (s0 == '')
        l.shift if (l[0][0, 1] == '0')

        return if (l.empty?)

        l2 = l.reverse

        a = {}
        c = 0
        1000.times \
        {
                |i| 
                f, j, r0, r = adj(l2)
                if (f) then
                        x = [j, r0]
                        a[x] = {} if (a[x].nil?)
                        a[x][r] = 0 if (a[x][r].nil?)
                        a[x][r] += 1
                        c += 1
                end
        }
#       puts
#       p(s0)
#       p(l)
#       p(l2)
#       puts
#       p(a)
        return if (a.empty?)

        m = a.keys.map { |x| x[0] }.max
        return n, m
end

n = 3
m = 0
loop \
{
        l = seq(n)
        next if (l.nil?)
        m = [l[1], m].max
        p(l + [m])
        n += 2
}