3 ms·

I wrote a 11811-character regex for divisibility by 7 back in August 2008: http://web.mit.edu/andersk/Public/regex http://web.mit.edu/andersk/Public/regex

• eru 11y ago
  Do you have the source to the program you wrote the regex with? (Or did you write it by hand?)
• fizbin 11y ago
  And unlike the one on stackexchange, it's actually correct! (I have a regex -> DFA compiler here that I just threw your regex through. Seven states, connected as expected)