Apr 18, 2025
diff --git a/9-regular-expressions/15-regexp-catastrophic-backtracking/article.md b/9-regular-expressions/15-regexp-catastrophic-backtracking/article.md
    ...And so on.


 There are many ways to split a sequence of digits `123456789` into numbers. To be precise, there are <code>2<sup>n</sup>-1</code>, where `n` is the length of the sequence.
 There are many ways to split a sequence of digits `123456789` into numbers. To be precise, there are <code>2<sup>n-1</sup></code>, where `n` is the length of the sequence.

 - For `123456789` we have `n=9`, that gives511 combinations.
 - For a longer sequence with `n=20` there are about one million (1048575) combinations.
 - For `n=30` - a thousand times more (1073741823 combinations).
 - For `123456789` we have `n=9`, that gives256 combinations.
 - For a longer sequence with `n=21` there are about one million (1048576) combinations.
 - For `n=31` - a thousand times more (1073741824 combinations).

 Trying each of them is exactly the reason why the search takes so long.
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Expand Up		@@ -150,11 +150,11 @@ Here's what the regexp engine does:
		...And so on.


		There are many ways to split a sequence of digits `123456789` into numbers. To be precise, there are <code>2<sup>n</sup>-1</code>, where `n` is the length of the sequence.
		There are many ways to split a sequence of digits `123456789` into numbers. To be precise, there are <code>2<sup>n-1</sup></code>, where `n` is the length of the sequence.

		- For `123456789` we have `n=9`, that gives511 combinations.
		- For a longer sequence with `n=20` there are about one million (1048575) combinations.
		- For `n=30` - a thousand times more (1073741823 combinations).
		- For `123456789` we have `n=9`, that gives256 combinations.
		- For a longer sequence with `n=21` there are about one million (1048576) combinations.
		- For `n=31` - a thousand times more (1073741824 combinations).

		Trying each of them is exactly the reason why the search takes so long.

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