Exponentiation by Squaring

exponentiation_by_squaring.rb

# frozen_string_literal: true

require 'benchmark'

def repeat_naive(str, num)
  result = ''
  str = str.to_s
  num = num.to_i
  while num.nonzero?
    result += str
    num -= 1
  end
  result
end

def repeat(str, num)
  result = ''
  str = str.to_s
  num = num.to_i
  while num.nonzero?
    result += str if num.odd?
    str += str
    num /= 2
  end
  result
end

Benchmark.bmbm do |x|
  x.report('näive') { repeat_naive('Hello!', 1000) }
  x.report('EBS') { repeat('Hello!', 1000) }
  x.report('*') { 'Hello!' * 1000 }
end