@Doorknob An interesting challenge would be:
You have an input like "II,IIII,IIIIII,IIIIIIIIIIIIIII"
Write a regex that matches the input if it's sorted.
Case1:
"II,IIII,IIIIII,IIIIIIIIIIIIIII" -> true
Case2:
"II,IIII,IIIIII,IIIIIIIIIIIIIII,II" -> false