Comments on: War Dialling ? http://www.sourceguru.net/archives/111 Mon, 01 Dec 2008 22:15:50 +0000 http://wordpress.org/?v=2.6.3 By: Paul http://www.sourceguru.net/archives/111#comment-15620 Paul Tue, 08 Jan 2008 16:35:55 +0000 http://www.sourceguru.net/archives/111#comment-15620 I haven't tried this, but what about the constraint that the first number must be >= 27? You didn't mention that one, Nils, but I'm guessing you included it. I haven’t tried this, but what about the constraint that the first number must be >= 27? You didn’t mention that one, Nils, but I’m guessing you included it.

]]> By: Nils http://www.sourceguru.net/archives/111#comment-15605 Nils Mon, 07 Jan 2008 22:04:04 +0000 http://www.sourceguru.net/archives/111#comment-15605 I also wrote a small PHP script. I assume that the second number (of 4 digits) must be greater than 724 (724 are added), the first digit of the second number must be 0 or 1 because 8000 are subtracted and the STD is 0161 so the first part of the checksum is 8. With these assumptions there are only 4077 possible numbers that could be correct (checksum must be 29-8=21). I also wrote a small PHP script.

I assume that the second number (of 4 digits) must be greater than 724 (724 are added), the first digit of the second number must be 0 or 1 because 8000 are subtracted and the STD is 0161 so the first part of the checksum is 8.

With these assumptions there are only 4077 possible numbers that could be correct (checksum must be 29-8=21).

]]> By: jldugger http://www.sourceguru.net/archives/111#comment-15604 jldugger Mon, 07 Jan 2008 20:17:47 +0000 http://www.sourceguru.net/archives/111#comment-15604 There's a ton more of these types of problems at Project Euler. I've started on them recently, and I'm not sure if it's that they're just problems 7 years old but they don't yet seem to need intelligent programming to solve. The hardest one so far was the one where I tried using a big int library, and wound up just using 64 bit arithmatic. There’s a ton more of these types of problems at Project Euler. I’ve started on them recently, and I’m not sure if it’s that they’re just problems 7 years old but they don’t yet seem to need intelligent programming to solve. The hardest one so far was the one where I tried using a big int library, and wound up just using 64 bit arithmatic.

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