Regex Golf Answers (http://regex.alf.nu/) HN: https://news.ycombinator.com/item?id=6941231

answers.md

1. Plain Strings (207): foo
2. Anchors (208): k$
3. Ranges (202): ^[a-f]*$
4. Backrefs (201): (...).*\1
5. Abba (169): ^(.(?!(ll|ss|mm|rr|tt|ff|cc|bb)))*$|^n|ef
6. A man, a plan (177): ^(.)[^p].*\1$
7. Prime (286): ^(?!(..+)\1+$)
8. Four (199): (.)(.\1){3}
9. Order (198): ^[^o].....?$
10. Triples (507): (^39|^44)|(^([0369]|([147][0369]*[258])|(([258]|[147][0369]*[147])([0369]*|[258][0369]*[147])([147]|[258][0369]*[258])))*$)
11. Glob (364): ^((\*(er|f|i|p|t|v))|(b|c(h|o|r)|do|l|mi|p(a|r|u)|re|w))
12. Balance (286): ^(<(<(<(<(<(<<>>)*>)*>)*>)*>)*>)*$
13. Powers (56): ^((((((((((x)\10?)\9?)\8?)\7?)\6?)\5?)\4?)\3?)\2?)\1?$

Total Score: 3060

tweaking 2 of my top 100 candidates has generated these 596 and 595 point solutions for triples:

00(3|6|9|15|$)|.1.+4|.17|[04].2|55
[07][0269]+3?$|0.2|1.4|3.*7.|58|015

Nice work. Makes it look hopeful that you might beat 596.

Here it is compared with the similar published 596 point solution:

00($|3|6|9|15)|[04].2|.1.+4|.17|55
00($|3|6|9|12|15)|4.2|.1.+4|.17|55

And here is your 595 compared with the other published 596:

[07][0269]+3?$|[02-5][123][257]|55
[07][0269]+3?$|0.2|1.4|3.*7.|58|015

Nice. Making progress bbarry.

I hope this computer search does yield a saving in the end. It certainly seems possible.

Balance (454): .{37}|^(<(..(?!<.>$))*>)*$

Edit: Used to score 294, now 454 with new scoring

Order (198): ^[^o].{1,5}$

Same points, but a better using shorter negating syntax and numbers instead of multiple dots.

Triples (543): ^(0+[0369]|0{7}1[25]|06.*|1.*[60]|3[1269].*[478]|32.*|4[04].*|7[14].*|8[17].*|9[05].*)$

Triples (574): ^(.*[07](6|1[25]|[056][^58])|([349][^378]|[78][147]).*)$

Triples (523): ^([0369]|[258][0369]*[147]|([147]|[258][0369]*[258])([0369]|[147][0369]*[258])*([147][0369]*[147]|[258]))*$

(I designed a DFA and converted it using Kleene's algorithm, it's the most correct way to do it although not the one that scores the most)

Balance (444): ^(<(<(<(<(<(<(<>)>)>)>)>)>)>)$

Balance (446): ^(<(<(<(<(<(<.*>)*>)*>)*>)*>)*>)*$

Balance (447): ^(<(<(<(<(<(...)*>)*>)*>)*>)*>)*$

Powers 2(82): ^(x{81})+$|^x$|^(x{3}){1,9}$

Powers 2: ^(.|(...)+)$ (88)

Matches 1 test that it shouldn't, but still the most points I could get within reasonable time. Several ways to get 86pts otherwise.

Long Count = 256 points: ((.+)0\2+1){8}

561 on Triples... might need optimized/refined

[0562][04]$|[30]03$|0[4629]$|12$|015$|[48]7$|9005$|7[6825]$|31$|58$

glob-- ^(*(er|f|i|p|t|v)|b|c(?!a)|d(?!i)|l|mi|p|re|w)

Triples (589): 003|009|0.2|015|00$|06|1.4|4.2|55|.17|819

Power 2: ^(?!xx$|(x(xxx)+)\1*$)

Power 2:^(?!((xxx)+x|xx)\1*$)

It never ends: u\b

I've updated Best known Regex Golf solutions. The current Classic level set is fully covered. It's now in table format, including full credits and date-time stamps, a history of gradual improvements for most of the levels, and some extra bonus information.

I have intentionally not updated the Teukon level set solutions compilation, nor posted one for Holiday, as with the release of functioning high score lists in the newly brought back Regex Golf site, to do so would further taint the high scores with people who simply Google it and copy the solutions. This is not an ideal situation by any means, as I'd really like for everyone to be able to benefit from this knowledge if they so desire, but given the way the on-site high score lists currently function, I see no alternative. Having date-time stamps in the on-site high score lists would be a good start towards fixing this problem.

Abba (193): ^(?!.*(.)(.)\2\1)

Hi @jonathanmorley, can you enlighten me why (?!(.)(.)\2\1) matches abba? isn't it matching any string that does not have a 4 characters palindrome?