Repeating letters

Question

Hello everyone. I think I messed up in the understanding of groups and special sequences. I need to get repeating characters from my string as output, but it looks like that my regex doesn't work. Any recommendations?
https://code.sololearn.com/c8IqsxqqhPoB/?ref=app

Answer 1

I don’t know what rejex is. I would just use a four loop. Rejex is probably using that in the background anyway.