split_digits.rb

require 'benchmark'

class Numeric
  def split_digits_1(base = 10)
    # head, last = self.divmod(base)
    head = self / base
    last = self % base
    head < base ? [head, last] : head.split_digits_1(base).push(last)
  end

  def split_digits_2(base = 10)
    total, result = self, []

    while total > 0
      fraction = total % base
      total /= base
      result << fraction
    end

    result.reverse
  end

  def split_digits_3(base = 10)
    total, result = self, []

    while total > 0
      fraction = total % base
      total /= base
      result.unshift fraction
    end

    result
  end

  def split_digits_4(base = 10)
    total, result = self, []

    while total > 0
      total, fraction = total.divmod(base)
      result << fraction
    end

    result.reverse
  end
end

N = 100e100.to_i
TIMES = 10_000

p N.split_digits_1
p N.split_digits_2
p N.split_digits_3
p N.split_digits_4

Benchmark.bmbm do |b|
  b.report '1' do
    TIMES.times do
      N.split_digits_1
    end
  end

  b.report '2' do
    TIMES.times do
      N.split_digits_2
    end
  end

  b.report '3' do
    TIMES.times do
      N.split_digits_3
    end
  end

  b.report '4' do
    TIMES.times do
      N.split_digits_3
    end
  end
end

iota ~prog/ruby/bench % ruby split_digits.rb
[9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 0, 4, 9, 5, 1, 3, 2, 6, 5, 2, 4, 5, 3, 3, 6, 6, 2, 8, 4, 4, 6, 8, 4, 2, 7, 1, 9, 9, 2, 4, 1, 5, 0, 0, 0, 6, 1, 2, 9, 9, 9, 5, 9, 7, 4, 7, 3, 1, 9, 9, 3, 4, 5, 2, 1, 8, 0, 7, 8, 9, 9, 1, 1, 3, 0, 3, 2, 6, 1, 2, 9, 4, 4, 8, 1, 5, 1, 1, 5, 4, 6, 8, 8, 0]
[9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 0, 4, 9, 5, 1, 3, 2, 6, 5, 2, 4, 5, 3, 3, 6, 6, 2, 8, 4, 4, 6, 8, 4, 2, 7, 1, 9, 9, 2, 4, 1, 5, 0, 0, 0, 6, 1, 2, 9, 9, 9, 5, 9, 7, 4, 7, 3, 1, 9, 9, 3, 4, 5, 2, 1, 8, 0, 7, 8, 9, 9, 1, 1, 3, 0, 3, 2, 6, 1, 2, 9, 4, 4, 8, 1, 5, 1, 1, 5, 4, 6, 8, 8, 0]
[9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 0, 4, 9, 5, 1, 3, 2, 6, 5, 2, 4, 5, 3, 3, 6, 6, 2, 8, 4, 4, 6, 8, 4, 2, 7, 1, 9, 9, 2, 4, 1, 5, 0, 0, 0, 6, 1, 2, 9, 9, 9, 5, 9, 7, 4, 7, 3, 1, 9, 9, 3, 4, 5, 2, 1, 8, 0, 7, 8, 9, 9, 1, 1, 3, 0, 3, 2, 6, 1, 2, 9, 4, 4, 8, 1, 5, 1, 1, 5, 4, 6, 8, 8, 0]
[9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 0, 4, 9, 5, 1, 3, 2, 6, 5, 2, 4, 5, 3, 3, 6, 6, 2, 8, 4, 4, 6, 8, 4, 2, 7, 1, 9, 9, 2, 4, 1, 5, 0, 0, 0, 6, 1, 2, 9, 9, 9, 5, 9, 7, 4, 7, 3, 1, 9, 9, 3, 4, 5, 2, 1, 8, 0, 7, 8, 9, 9, 1, 1, 3, 0, 3, 2, 6, 1, 2, 9, 4, 4, 8, 1, 5, 1, 1, 5, 4, 6, 8, 8, 0]
Rehearsal -------------------------------------
1   1.170000   0.000000   1.170000 (  1.184450)
2   1.140000   0.000000   1.140000 (  1.139748)
3   1.190000   0.000000   1.190000 (  1.193600)
4   1.190000   0.010000   1.200000 (  1.198022)
---------------------------- total: 4.700000sec

        user     system      total        real
1   1.180000   0.000000   1.180000 (  1.178914)
2   1.150000   0.000000   1.150000 (  1.149533)
3   1.190000   0.000000   1.190000 (  1.191845)
4   1.190000   0.000000   1.190000 (  1.199869)