FindDigit.rb

=begin

The function findDigit takes two numbers as input, num and nth. It outputs
the nth digit of num (counting from right to left).

#Note

If num is negative, ignore its sign and treat it as a positive value.
If nth is not positive, return -1.
Keep in mind that 42 = 00042. This means that findDigit(42, 5) would return 0.
#Examples

findDigit(5673, 4)     returns 5
findDigit(129, 2)      returns 2
findDigit(-2825, 3)    returns 8
findDigit(-456, 4)     returns 0
findDigit(0, 20)       returns 0
findDigit(65, 0)       returns -1
findDigit(24, -8)      returns -1

=end

# My Solution
def find_digit(num, nth)
  num = num.abs
  return -1 if nth < 1
  return 0 if nth > num.to_s.length
  num.to_s[-nth].to_i
end

# Better Solution
def find_digit(num, nth)
  unless nth <= 0
    num.to_s[- nth].to_i
  else
    -1
  end
end