..if you follow the belgium instructions - you bascially do the same as right-clicking on a user - but now directly through the http interface (which is used at the back).
What you see is the list of files/dirs which the user specifically asked to be shared to the world at large through the application.
So unless there is something not said in the pandora article - what is described is exactly what those P2P apps are designed to do. Share what is designated shared... it just shows you things little closer to the metal .
Of the top of my head:
for a number n digits long (ignoring the last entry) we have 10^n combinations and the average value in each position is 4.5 and each number has n digits:
=> n * 10^n * average value of a digit (4.5) +1
or - more constructional:
0...9 = 4*10+5 = 1 * 45
00..99 = 10x(0..9) + 10x(0..9) = 2 * 10 * 45
i.e. each row has all permutations.
000...999 =.. = 3 * 10 * 10 * 45
0000....9999 =.. = 4 * 10 * 10 * 10 * 45
with n=ln(N)/ln(10)
=> n * 10^(n-1) * sum(0..9)
and then add one for the million (inclusive).
=> n * 10^(n-1) * sum(0..9) + 1
The actual riddle is very cute - as it can be done
with a few lines of code - or by just thinking
logically - and calculating it straight out. (and if you realize that leading zeros do not foil the fun as they do not add - it gets positively neat).
But still a bit easy for a 15-16 year old I would recon.
If you are not scared of using perl; the mgetty(vgetty) included with the varies unix fax options:
ftp://ftp.leo.org/pub/comp/os/unix/networking/mg et ty/.
Does the trick quite nicely. VCOP (see sourceforge) gives you some perl glue code to make things a bit easier.
But I found that using vgetty raw from mod_perl was just as easy. You do need to be careful in what modem you use - and will find that the cheap cards are either not compatible enough - or have limitations like 15 seconds of sound.
Fore something way neater: see:
http://www.quicknet.net/
which has a linejack card which can do the 'world' - including complex caller interaction and dsp based detection. I found it to work reasonable on linux (RH7.0) and very robust on FreeBSD 4.x - but for your application it is probably overkill.
This might sound silly - but eBay has usually very cheap scope's going. You need some expertize to judge their quality - and some patience. But you should be able to get away with a 1000mHz dual
channel analog scope for under a 100$. I needed
about 2 months of systematically bidding up to 75 dollars on each decent one.
As for a digital scope - I found www.activewireinc.com a most excelent toy - it is basically a 8051 running at decent speed with 16 inputs/outputs - and easily clockable. At 10kHz you can sample from the PC (works with FreeBSD, NetBSD and linux/windoze) at higher rates you simply write a bit of 'c' code you download into the device to do the capture.
http://www.oceanoptics.com makes a great PCI card which has good IO and easy to integrate.
Another option is to spend 50-150 dollars on a third hand GPIB based A/D device. Ebay has lots of them and add a NI card to your PC.
Dw
with NetBSD and FreeBSD. Given how clean they work - I suspect linux to be fine. Usually with some intel procesor board. It works well. The typical usage was to have 8 slots with a 4 port ethernet card - and combining this with DummyNet. And then letting the processor netboot off its own ethernet and then act as a packet delay line of sorts.
Do a search in google for 'PICMG' to find a whole range of those. One word of warning - you may need
to add some special (userland) hacks for the watchdog - they can be quite a pain - and you almost certainly will need to learn about serial consoles. My experience with the latter and Linux is not too good:-)
Dw
Slashdot Mirror
..if you follow the belgium instructions - you bascially do the same as right-clicking on a user - but now directly through the http interface (which is used at the back).
What you see is the list of files/dirs which the user specifically asked to be shared to the world at large through the application.
So unless there is something not said in the pandora article - what is described is exactly what those P2P apps are designed to do. Share what is designated shared... it just shows you things little closer to the metal .
Dw
Of the top of my head:
.. = 3 * 10 * 10 * 45
.. = 4 * 10 * 10 * 10 * 45
for a number n digits long (ignoring the last entry) we have 10^n combinations and the average value in each position is 4.5 and each number has n digits:
=> n * 10^n * average value of a digit (4.5) +1
or - more constructional:
0...9 = 4*10+5 = 1 * 45
00..99 = 10x(0..9) + 10x(0..9) = 2 * 10 * 45
i.e. each row has all permutations.
000...999 =
0000....9999 =
with n=ln(N)/ln(10)
=> n * 10^(n-1) * sum(0..9)
and then add one for the million (inclusive).
=> n * 10^(n-1) * sum(0..9) + 1
Gives you all the detail you'd ever want.
The actual riddle is very cute - as it can be done with a few lines of code - or by just thinking logically - and calculating it straight out. (and if you realize that leading zeros do not foil the fun as they do not add - it gets positively neat).
But still a bit easy for a 15-16 year old I would recon.
If you are not scared of using perl; the mgetty(vgetty) included with the varies unix fax options:
g et ty/.
ftp://ftp.leo.org/pub/comp/os/unix/networking/m
Does the trick quite nicely. VCOP (see sourceforge) gives you some perl glue code to make things a bit easier.
But I found that using vgetty raw from mod_perl was just as easy. You do need to be careful in what modem you use - and will find that the cheap cards are either not compatible enough - or have limitations like 15 seconds of sound.
Fore something way neater: see:
http://www.quicknet.net/
which has a linejack card which can do the 'world' - including complex caller interaction and dsp based detection. I found it to work reasonable on linux (RH7.0) and very robust on FreeBSD 4.x - but for your application it is probably overkill.
Dw
This might sound silly - but eBay has usually very cheap scope's going. You need some expertize to judge their quality - and some patience. But you should be able to get away with a 1000mHz dual channel analog scope for under a 100$. I needed about 2 months of systematically bidding up to 75 dollars on each decent one. As for a digital scope - I found www.activewireinc.com a most excelent toy - it is basically a 8051 running at decent speed with 16 inputs/outputs - and easily clockable. At 10kHz you can sample from the PC (works with FreeBSD, NetBSD and linux/windoze) at higher rates you simply write a bit of 'c' code you download into the device to do the capture. http://www.oceanoptics.com makes a great PCI card which has good IO and easy to integrate. Another option is to spend 50-150 dollars on a third hand GPIB based A/D device. Ebay has lots of them and add a NI card to your PC. Dw
Try dovebid: www.dovebid.com. We've had a lot of luck with them. They are the sort of auctioneer who does the whole of WebVan, AlliedSteel or larger.
- http://www.modindsol.com/product_detail.cfm?PRODU
C TID=114
-
http://www.icp-oem.com/passive_backplanes.html
with NetBSD and FreeBSD. Given how clean they work - I suspect linux to be fine. Usually with some intel procesor board. It works well. The typical usage was to have 8 slots with a 4 port ethernet card - and combining this with DummyNet. And then letting the processor netboot off its own ethernet and then act as a packet delay line of sorts. Do a search in google for 'PICMG' to find a whole range of those. One word of warning - you may need to add some special (userland) hacks for the watchdog - they can be quite a pain - and you almost certainly will need to learn about serial consoles. My experience with the latter and Linux is not too good