统计0到n的所有数字中1出现的次数_Ruby_编程开发_程序员俱乐部

class="java" name="code">
require 'test/unit'

class TestCountN < Test::Unit::TestCase

  def test
    assert_equal 6, count(13)
  end

end

def add_all_number_to_str n
  str = ""
  for i in 1..n
    str += i.to_s
  end
  str
end

def count n
  c = 0
  add_all_number_to_str(n).each_char {|x| c=c+1 if(x.to_i)==1}
  c
end