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Quiz · 5 questions

👑 Advanced Patterns & Mastery

Atomic groups, recursion, ReDoS, optimization — and knowing when to put regex down

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Quiz

01What does an atomic group (?>...) do that a regular group doesn't?
Hint
Once committed to a match, refuses to look back.
02Why does the pattern (a+)+b hang on input 'a'*30 (no 'b')?
Hint
Nested quantifiers + matching same chars = trouble.
03Why is RE2 (used by Go and ripgrep) immune to ReDoS?
Hint
DFA-class engines trade features for time guarantees.
04Which of these is the safest replacement for .*?X?
Hint
If there's only one direction, no backtracking is needed.
05What's the most important sign that you should stop using regex and reach for a parser?
Hint
If you need to count or balance, regex isn't the right tool.
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