一道关于Ruby的面试题

# test case
def check(i)
  if i.zero?
     false
  elsif 1 == i % 10
     true
  else
     check(i / 10)
  end
end

# the f function
def f(range = 0..0)
  if range.is_a? Range
    raise "Invalid range values. Must be integer." unless range.begin.is_a?(Integer) and range.begin.is_a?(Integer)
    raise "Range values must be bigger than -1" unless range.begin >= 0 and range.end >= 0
    raise "Range begin must not be bigger than the end" unless range.begin <= range.end
    range.inject(0) do |sum, i|
       if check(i)
          sum.succ
       else
          sum
       end
    end
  else
    raise "Please input range"
  end
end

# test
puts f(0..ARGV[0].to_i)

python 代码

import math  
  
def length11(n):  
    return int( math.log10(n) )  
  
def first(n):  
    return n/pow(10, length11(n))  
def tail(n):  
    return n % pow(10, length11(n))  
  
def f9(k):  
    if k == 0:  
        return 0  
    return pow(10, k-1) + 10*f9(k-1)  
  
def f1(n):  
    if first(n) == 1:  
        return tail(n) + 1  
    else:  
        return pow(10, length11(n))  
  
def cal(n):  
    if n== 0:  
        return 0  
    if n <= 9:  
        return 1  
    return f1(n) + first(n) * f9(length11(n))+ cal(tail(n))  
  
  
print cal(213)  
print cal(10) 

def get_one_count(from, to, base=10)
  sum = 0  
  
  for n in (from .. to) do    
    begin
      r =  n % base
      n = (n / base).floor
      sum += 1 if r == 1
    end while n != 0    
  end
  
  return sum
end

puts get_one_count(0, 13)