straightforward, accept one repetition but not two.

print grep { /(\d).*\1/ && ! /(\d).*\1.*\1/ } map {sprintf "%04d",$_} 
+(0..9999)

[download]

Tried to do it in one regex but I couldn't find out how to negate the match \1, [^\1] obviously doesnt work and all negative look aheads get confused by the end of string...

Cheers Rolf

UPDATE: sorry nothing new :( ...Re: Find duplicate digits

In reply to Re: Find duplicate digits by LanX
in thread Find duplicate digits by Anonymous Monk

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