From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Dresser Date: Fri, 11 Apr 2003 19:09:35 +0000 Subject: Re: [ANNOUNCE] udev 0.1 release Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Fri, 11 Apr 2003, John Bradford wrote: > [Puzzle] > > Say the power supply had five 5.25" drive power connecters, how many 1 > into 3 power cable splitters would you need to connect all 4000 disks? never seen a 3 into 1, but we'll play along. every 3 in 1 connector you use, triples your connections, go two levels deep, it's 3 * 3 = 9, pretty obvious. I'm just going to use one connector off the power supply for now. 3 ^ 7 = 2187 So we'll use another two off the PS and not go as deep 2 * (3 ^ 6) = 1458 2187 + 1458 = 3645 Need another 4000 - 3645 = 355 3 ^ 5 = 243. Need another 355 - 243 = 112 Use another connector 3 ^ 4 = 81 Need another 112 - 81 = 31. So close but out of first level connectors. So I put a 3 way splitter on one of those. 3 ^ 3 = 27. argh! Need another 31+1(had to use up a connector) - 27 = 5. So I put another 3 way splitter. 5 + 1 = 6. 3 ^ 1 = 3. Need another three. Take one off, pass it around, and we're almost done. Add another 3 way splitter, we've got two connectors left over, and everything is plugged in. Turn on the ps. Boom, done. Now, to count up the total. level 1 = 1 = 1 level 2 = 1 + 3 = 4 Level 3 = 4 + 9 = 13 Level 4 = 13 + 27 = 40 Level 5 = 40 + 81 = 121 Level 6 = 121 + 243 = 324 Level 7 = 324 + 729 = 1053 So anyways, I used one level 7, two level 6's, one level 5, one level 4, one level 1, one level 3, one level 1, another level 1 and finally another level 1 total of 1053 + 324 + 324 + 121 + 40 + 1 + 13 + 1 + 1 + 1 I come up with 1879. If i'm too high, that's to account for the fact you broke some connectors at some point, so you used the spares. If i'm too low, that's to account for the fact that out of 4000 drives, a few are going to be DOA and you couldn't hook them up anyways. Someone PLEASE tell me the simpler way to do this. Mike ------------------------------------------------------- This SF.net email is sponsored by: Etnus, makers of TotalView, The debugger for complex code. Debugging C/C++ programs can leave you feeling lost and disoriented. TotalView can help you find your way. Available on major UNIX and Linux platforms. Try it free. www.etnus.com _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel