/me tries to figure out how to do a spoiler in web-space...

Spoiler follows!...


 
 
 

/^(1[01]*1|0[01]*0)$/

or, if I can use backreferences (wasn't clear if grouping meant _only_ grouping): 

/^([01])[01]*\1$/

-dlc

In reply to RE: Fun Regex Exercise by dchetlin
in thread Fun Regex Exercise by japhy

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