Instantly share code, notes, and snippets.

# teukon/gist:16b6de379907bb2a3aa4 Secret

Last active December 3, 2018 15:12
Show Gist options
• Save teukon/16b6de379907bb2a3aa4 to your computer and use it in GitHub Desktop.
Regex Golf - Unofficial Bonus Levels

### Regex Golf - Unofficial Bonus Levels

1. Subtraction Quantify with care.
2. Typist With apologies to Dr. Dvorak.
4. Anyway Old MacDonald had a farm...
5. Tic-tac-toe Don't forget the horizontals.
7. Matryoshka Pay attention to detail.
8. Euclid Greed is good.
9. Latin squares No mathematics; just logic and reasoning.
10. Dominoes Caution! Rabbit holes.

Each problem has a robust solution (can be done "without cheating"), unlike "A man, a plan", "Glob", and "Balance" from the original set. In each case, the pattern should be unambiguous. A solution to a problem is considered robust if it conforms to this pattern for any string matching the problem's domain regex:

Level Domain regex
Subtraction `^x+ - x+ = x+\$`
Typist `^[a-z]+\$`
Addition `^x+ \+ x+ = x+ \+ x+\$`
Anyway `^[a-z]+\$`
Tic-tac-toe `^[\.OX]{3} [\.OX]{3} [\.OX]{3}\$`
Modulus `^x+ % x+ = x+\$`
Matryoshka `^([a-z]+ )*[a-z]+\$`
Euclid `^gcd\(x+, x+\) = x+\$`
Latin squares `^[a-z]{4} [a-z]{4} [a-z]{4} [a-z]{4}\$`
Dominoes `^([0-6]{2} )*[0-6]{2}\$`

Please refrain from posting solutions here until the thread is well underway (20+ posts). Questions, total scores, and gentle hints are ok.

A warm thank you to Davidebyzero for helping me refine each of these problems, and for coming up with some brilliant solutions. Our testing and development notes can be found here and here (caution: spoilers).

### teukon commented Feb 25, 2014

Welcome! :)

Yes, the difficulty in this one is more to do with pinning down the precise pattern than in building the regex or in compressing it. Focus on the "on" and "sad" lines in particular.

Good luck!