comefrom: <doocs>2007.Find Original Array From Doubled Array_1.py
code: def findOriginalArray( changed: List[int]) -> List[int]:
      if len(changed) % 2 != 0:
          return []
      n = 100010
      counter = [0] * n
      for x in changed:
          counter[x] += 1
      if counter[0] % 2 != 0:
          return []
      res = [0] * (counter[0] // 2)
      for i in range(1, n):
          if counter[i] == 0:
              continue
          if i * 2 > n or counter[i] > counter[i * 2]:
              return []
          res.extend([i] * counter[i])
          counter[i * 2] -= counter[i]
      return res
masked: def sample_funcname ( var_0 : List [ int ] ) -> List [ int ] :
      if len ( var_0 ) % 2 != 0 :
          return [ ]
      var_7 = 100010
      var_8 = [ 0 ] * var_7
      for var_9 in var_0 :
          var_8 [ var_9 ] += 1
      if var_8 [ 0 ] % 2 != 0 :
          return [ ]
      var_11 = [ 0 ] * ( var_8 [ 0 ] // 2 )
      for var_13 in range ( 1 , var_7 ) :
          if var_8 [ var_13 ] == 0 :
              continue
          if var_13 * 2 > var_7 or var_8 [ var_13 ] > var_8 [ var_13 * 2 ] :
              return [ ]
          var_11.extend ( [ var_13 ] * var_8 [ var_13 ] )
          var_8 [ var_13 * 2 ] -= var_8 [ var_13 ]
      return var_11
  