Smallest number
Level: Beginner (score: 2)
Write a function that accepts a list of digits and returns the smallest number that can be created by combining unique digits.
Therefore, you have to ignore duplicated digits.
Examples:
[1] => 1
[7, 1] => 17
[1, 9, 5, 9, 1] => 159
Note: An empty input list [] should return 0.