*Update: I posted a wrap-up here*.

Here is an interesting coding challenge: write a counter function that counts from 1 to max but only returns numbers whose digits don’t repeat.

For example, part of the output would be:

- 8, 9, 10, 12 (11 is not valid)
- 98, 102, 103 (99, 100 and 101 are not valid)
- 5432, 5436, 5437 (5433, 5434 and 5435 are not valid)

Also:

- Display the biggest jump (in the sequences above, it’s 4: 98 -> 102)
- Display the total count of numbers
- Give these two values for max=10000

Post your solution in the comments or on your blog. All languages and all approaches (brute force or not) are welcome.

I’m curious to see if somebody can come up with a clever solution (I don’t have one)…