comefrom: <doocs>0357.Count Numbers with Unique Digits_1.py
code: def countNumbersWithUniqueDigits( n: int) -> int:
      if n == 0:
          return 1
      if n == 1:
          return 10
      ans, cur = 10, 9
      for i in range(n - 1):
          cur *= 9 - i
          ans += cur
      return ans
masked: def sample_funcname ( var_0 : int ) -> int :
      if var_0 == 0 :
          return 1
      if var_0 == 1 :
          return 10
      var_5 , var_7 = 10 , 9
      for var_9 in range ( var_0 - 1 ) :
          var_7 *= 9 - var_9
          var_5 += var_7
      return var_5
  