Re: Lovefilm, yes or no?
I'm not sure if that interview question thread proves you are all deranged nutters, maths geniuses or scarily good programmers. Probably a bit of each. Jeez, where has my "PHP For Beginners" book gone, it's not too late for a career in a meejabollix agency. Cheers, Peter On Apr 14, 2010 10:53 PM, "Ruud H.G. van Tol" wrote: ian wrote: > I was once asked at an interview 'how many digits of PI do you know?'. If phrased like that, I would ask "Decimal?" and then answer "ten", 0..9. -- Ruud
Re: Lovefilm, yes or no?
ian wrote: I was once asked at an interview 'how many digits of PI do you know?'. If phrased like that, I would ask "Decimal?" and then answer "ten", 0..9. -- Ruud
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 07:42:59PM +0200, Philip Newton wrote: > On Wed, Apr 14, 2010 at 19:31, David Cantrell wrote: > > On Wed, Apr 14, 2010 at 07:16:18PM +0200, Abigail wrote: > >> On Wed, Apr 14, 2010 at 04:23:48PM +0100, ian wrote: > >> > I was once asked at an interview 'how many digits of PI do you know?'. > >> "All of them - I just can't remember the order". > > An infinitely long sequence of them, I just don't know where it starts. > Ah - you have a proof that pi is normal, then! Just what > mathematicians have been searching for for ages! I thought it had been proven. Ah well. -- David Cantrell | Reality Engineer, Ministry of Information Do not be afraid of cooking, as your ingredients will know and misbehave -- Fergus Henderson
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 10:29, Abigail wrote:
> On Wed, Apr 14, 2010 at 09:47:14AM -0700, David Alban wrote:
>> On Wed, Apr 14, 2010 at 9:36 AM, Merijn Broeren wrote:
>> > Does 128! end in a zero? If so, how many?
>>
>> i would think that any factorial N! would end in zero if N > 9. but i
>> have no idea how many zeroes are at the end of <128!>.
>
>
> 5! multiples 2 and 5.
>
> The trick is to count the number of factors of 5.
It's worth noting explicitly that those factors of 5 work to create
trailing zeros because there is an excess of spare factors of 2 to
make 2*5=10.
> floor (128 / 5) + floor (128 / 25) + floor (128 / 125) = 25 + 5 + 1 = 31.
>
>
> $ perl -E'$,="*";say 1..128'|bc|perl -0ne's/\D+//g;print/0+$/g'|wc -c
> 31
Nice. Mathematica,
Sum[Floor[128/5^k], {k, Floor[Log[5, 128]]}]
31
Log[5, 128] is the log base 5 of 128, i.e. the number you need to
raise 5 to to get 128 (=3.01...). The integer component of that
(Floor[]) gives you then the number of factors of five in 128 (=3).
The bit in the Sum[] is an iterator (k=1..3) creating a list {25, 5,
1} whose sum is 31.
Paul
> Abigail
>
Re: Lovefilm, yes or no?
On 14 Apr 2010, at 17:47, David Alban wrote: > i would think that any factorial N! would end in zero if N > 9. but i > have no idea how many zeroes are at the end of <128!>. Well, just give it a crack then. That's the point of the question, to see how people think. This one's particularly good because it's got several obvious answers, all of which are wrong, and it shows how hard people think. The first thing to note is that multiples of ten have one zero, multiples of a hundred have two zeroes, and so on. So you are looking for all of the multiples of ten in the factorial. The traps are not noticing that 2*5 = 10 - which you fell into - and that 10*10 = 100. The general idea is to realise that a factorial is also the product of the prime factors of each number. That is: N! = 1 * 2 * 3 * 4 * 5 * 6 ... = 1 * 2 * 3 * 2*2 * 5 * 2*3 ... = 2**a * 3**b * 5**c * 7**d ... And then to realise that a >= b >= c >= d, and so you care about the value of c (as there will always be enough twos to multiply by all the fives you can find to make tens.) So, there are int(128/5) = 25 multiples of five, int(128/5**2) = 5 multiples of 25, and int(128/5**3) multiples of 125. So c = 25 + 5 + 1 = 31. So I reckon that 128! has 31 zeroes on the end. Double-checking on a computer: >>> reduce(lambda x, y: x * y, range(1,129)) % 10**31 0L >>> reduce(lambda x, y: x * y, range(1,129)) % 10**32 8000L There is probably some neat trick with logarithms to calculate the number of zeros at the end of arbitrary N!, but I'm not a mathematician.
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 19:31, David Cantrell wrote: > On Wed, Apr 14, 2010 at 07:16:18PM +0200, Abigail wrote: >> On Wed, Apr 14, 2010 at 04:23:48PM +0100, ian wrote: >> > I was once asked at an interview 'how many digits of PI do you know?'. >> "All of them - I just can't remember the order". > > An infinitely long sequence of them, I just don't know where it starts. Ah - you have a proof that pi is normal, then! Just what mathematicians have been searching for for ages! Cheers, Philip -- Philip Newton
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 07:16:18PM +0200, Abigail wrote: > On Wed, Apr 14, 2010 at 04:23:48PM +0100, ian wrote: > > I was once asked at an interview 'how many digits of PI do you know?'. > "All of them - I just can't remember the order". An infinitely long sequence of them, I just don't know where it starts. -- David Cantrell | even more awesome than a panda-fur coat I remember when computers were frustrating because they did exactly what you told them to. That seems kinda quaint now. -- JD Baldwin, in the Monastery
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 09:47:14AM -0700, David Alban wrote: > On Wed, Apr 14, 2010 at 9:36 AM, Merijn Broeren wrote: > > Does 128! end in a zero? If so, how many? > > i would think that any factorial N! would end in zero if N > 9. but i > have no idea how many zeroes are at the end of <128!>. 5! multiples 2 and 5. The trick is to count the number of factors of 5. floor (128 / 5) + floor (128 / 25) + floor (128 / 125) = 25 + 5 + 1 = 31. $ perl -E'$,="*";say 1..128'|bc|perl -0ne's/\D+//g;print/0+$/g'|wc -c 31 Abigail
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 04:23:48PM +0100, ian wrote: > On 14/04/2010 14:05, Peter Edwards wrote: > ... >> >> I know a couple of people not on this list, one who joined in the last 6 >> months and seems happy enough there, another who interviewed for a perm job >> a couple of weeks ago and didn't get it. You takes your pick... >> >> Funniest interview question I heard of recently (not Lovefilm) was: >> "What's two to the power 14" >> As in, work out the answer there and then, not type in perl -e 'print >> 2**14, "\n"' as eny fule kno >> >> Cheers, Peter > > I was once asked at an interview 'how many digits of PI do you know?'. "All of them - I just can't remember the order". Abigail
Re: Lovefilm, yes or no?
On 14 April 2010 17:47, David Alban wrote: > i would think that any factorial N! would end in zero if N > 9. but i > have no idea how many zeroes are at the end of <128!>. Surely you mean if N > 4?
Re: Lovefilm, yes or no?
i would think that any factorial N! would end in zero if N > 9. but i have no idea how many zeroes are at the end of <128!>. On Wed, Apr 14, 2010 at 9:36 AM, Merijn Broeren wrote: > Does 128! end in a zero? If so, how many? -- Live in a world of your own, but always welcome visitors.
Re: Lovefilm, yes or no?
Quoting Peter Edwards (pe...@dragonstaff.co.uk): > > Funniest interview question I heard of recently (not Lovefilm) was: > "What's two to the power 14" > As in, work out the answer there and then, not type in perl -e 'print > 2**14, "\n"' as eny fule kno > Does 128! end in a zero? If so, how many? It's a quite a nice question to walk through to the end and it might surprise you if you haven't seen it before. Cheers, -- Merijn Broeren | We take risks, we know we take them. Therefore, when things | come out against us, we have no cause for complaint. | - Scott, last journal entry, march 1912
Re: Emergency social: The Gunmakers, tomorrow evening (for Perl 5.12.0)
On Wed, Apr 14, 2010 at 04:41:52PM +0100, Nicholas Clark wrote: >short of extraordinary rendition. Also, Damian is happy with the timing, >as he completed the talk *before* the examples shown were still warnings >free on the current version of Perl 5 :-) Editing fail on my part. '*before*' should be '*while*'. And Damian's threat remains - his calendar remains nice and empty, giving him plenty of time to write more EVIL, and upload it to CPAN.* Nicholas Clark * Your CPAN is at risk if you do not keep up payments.
Re: Emergency social: The Gunmakers, tomorrow evening (for Perl 5.12.0)
On Wed, Apr 14, 2010 at 04:41:52PM +0100, Nicholas Clark wrote: > Perl 5.12.0 escaped onto CPAN on Monday night, a few hours after Damian's > talk: > > http://use.perl.org/article.pl?sid=10/04/13/1953252 > > Clearly this is an emergency. Although whether it's a good emergency or > bad emergency is debatable. But either way, it requires a social. > > The Gunmakers, Clerkenwell, Thursday 15th April 2010, from 6:30pm > http://london.randomness.org.uk/wiki.cgi?Gunmakers%2C_EC1R_5ET > > The food is good, the beer is good, and they've actually found a reason for > Twitter to exist: https://twitter.com/thegunmakers Sadly, I don't think I can make it. Please have a pint for me! -Jesse
Re: Lovefilm, yes or no?
On Wed, 14 Apr 2010, ian wrote: On 14/04/2010 14:05, Peter Edwards wrote: I was once asked at an interview 'how many digits of PI do you know?'. enough. although id much rather cancel pi out. which is why it is useful to know that pi*(10^7) seconds = 363.610261 days or approximately 1 year. hmm pie. http://isitpie.com/ -- bob walker buses should be purple and bendy
Emergency social: The Gunmakers, tomorrow evening (for Perl 5.12.0)
Perl 5.12.0 escaped onto CPAN on Monday night, a few hours after Damian's talk: http://use.perl.org/article.pl?sid=10/04/13/1953252 Clearly this is an emergency. Although whether it's a good emergency or bad emergency is debatable. But either way, it requires a social. The Gunmakers, Clerkenwell, Thursday 15th April 2010, from 6:30pm http://london.randomness.org.uk/wiki.cgi?Gunmakers%2C_EC1R_5ET The food is good, the beer is good, and they've actually found a reason for Twitter to exist: https://twitter.com/thegunmakers Just because the cause of the emergency is a four letter word doesn't mean that we're likely to talk about it much. After all, off topic remains off topic :-) Nicholas Clark PS Huge thanks to Jesse for herding cats for half a year to make this happen. (And big thanks to the all the cats involved in the herding process) Although time remains for Jesse to visit in person, it seems unlikely, short of extraordinary rendition. Also, Damian is happy with the timing, as he completed the talk *before* the examples shown were still warnings free on the current version of Perl 5 :-)
Re: Lovefilm, yes or no?
On 14 April 2010 16:23, ian wrote: > I was once asked at an interview 'how many digits of PI do you know?'. I would claim to know digits 100 to 150 and ask them to check them for me as I recited...
Re: Lovefilm, yes or no?
On 14/04/2010 14:05, Peter Edwards wrote: ... I know a couple of people not on this list, one who joined in the last 6 months and seems happy enough there, another who interviewed for a perm job a couple of weeks ago and didn't get it. You takes your pick... Funniest interview question I heard of recently (not Lovefilm) was: "What's two to the power 14" As in, work out the answer there and then, not type in perl -e 'print 2**14, "\n"' as eny fule kno Cheers, Peter I was once asked at an interview 'how many digits of PI do you know?'. At that time I could remember about 100 digits so I had a dilemma, would I do better in the interview if I recited all 100 or perhaps 10? Another fact that sticks in my mind, and has been useful for the odd meeting where someone wants a back of fag-packet calulation, is that one million seconds is 11 days 13 hours 46 minutes and 40 seconds. (and that 10,000,000 seconds is 115 days 17 hours 46 minutes and 40 seconds). Regards Ian
Re: Lovefilm, yes or no?
On 14 Apr 2010, at 16:06, Simon Cozens wrote: > I guess I should be the first to point out that, not only are there > people from Lovefilm reading this list, there are people from the BBC > reading it too. I /think/ that's just the Reith proxy - so it doesn't narrow it down too much :) Wasn't me - that narrows it down a tad more. -- Andy Armstrong, Hexten
Re: Lovefilm, yes or no?
On 14 April 2010 16:06, Simon Cozens wrote: > > I guess I should be the first to point out that, not only are there > people from Lovefilm reading this list, there are people from the BBC > reading it too. > Not many people have access to the proxy logs to look up Purple Bunny's X-Originating-IP, and anyway isn't having your employees push off for a more tempting job all part and parcel of working life? Cheers, Peter
Re: Lovefilm, yes or no?
On 14/04/2010 11:24, Pinky Weaselly wrote: > Sorry for anon email, but I don't want to announce to my employer that I've > been approached by lovefilm about a job. I guess I should be the first to point out that, not only are there people from Lovefilm reading this list, there are people from the BBC reading it too. -- The best book on programming for the layman is "Alice in Wonderland"; but that's because it's the best book on anything for the layman. - Alan Perlis
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 04:14:17PM +0200, Jonathan McKeown wrote: > On Wednesday 14 April 2010 15:05:51 Peter Edwards wrote: > > > Funniest interview question I heard of recently (not Lovefilm) was: > > "What's two to the power 14" > > As in, work out the answer there and then > > 2^10 (1024) is roughly 10^3, so 2^4 x 2^10 is roughly 16 thousand. If you > can't remember the power of two nearest to 16,000, you might have to work out > 16x24 and add it on - 240 plus 12x12. > Well I was going to point out that 2^10 is 1K (i.e. 1024) and therefore 2^14 is 16K but resisted - until now. I feel I should also contribute: 16*24 = 16*(25-1) = 4*4*25-16 = 400-16 = 384. Therefore 2^14 = 16384. QED > It's a slightly odd question, i suppose, but not exactly hard. Perhaps i'm an > old fart, but I'd expect most programmers to be able to answer that almost > without pausing for breath. > > (And I see Nick Clark has already answered while I was typing). > > Jonathan
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 04:14:17PM +0200, Jonathan McKeown wrote: > 2^10 (1024) is roughly 10^3, so 2^4 x 2^10 is roughly 16 thousand. If you > can't remember the power of two nearest to 16,000, you might have to work out > 16x24 and add it on - 240 plus 12x12. > > It's a slightly odd question, i suppose, but not exactly hard. Perhaps i'm an > old fart, but I'd expect most programmers to be able to answer that almost > without pausing for breath. If hexadecimal is acceptable, then I could answer 0x4000 straight away. In decimal, I'd have to figger it out, as 65536 / 2 / 2. But who uses decimal for constants like that? -- David Cantrell | Hero of the Information Age Irregular English: ladies glow; gentlemen perspire; brutes, oafs and athletes sweat
Re: Lovefilm, yes or no?
On 14 Apr 2010, at 22:03, Nicholas Clark wrote: > On Wed, Apr 14, 2010 at 02:05:51PM +0100, Peter Edwards wrote: > >> Funniest interview question I heard of recently (not Lovefilm) was: >> "What's two to the power 14" >> As in, work out the answer there and then, not type in perl -e 'print >> 2**14, "\n"' as eny fule kno > > 16384 > > (I admit that I did check that I can remember it correctly.) > > > I'm starting to think that that's actually quite a good question really. My Google phone interview (at 3am FFS) did a LOT of bit shifting type questions. -- Dave HodgkinsonMSN: daveh...@hotmail.com Site: http://www.davehodgkinson.com UK: +44 7768 490620 Blog: http://www.davehodgkinson.com/blog Photos: http://www.flickr.com/photos/davehodg
Re: Lovefilm, yes or no?
On Wednesday 14 April 2010 15:05:51 Peter Edwards wrote: > Funniest interview question I heard of recently (not Lovefilm) was: > "What's two to the power 14" > As in, work out the answer there and then 2^10 (1024) is roughly 10^3, so 2^4 x 2^10 is roughly 16 thousand. If you can't remember the power of two nearest to 16,000, you might have to work out 16x24 and add it on - 240 plus 12x12. It's a slightly odd question, i suppose, but not exactly hard. Perhaps i'm an old fart, but I'd expect most programmers to be able to answer that almost without pausing for breath. (And I see Nick Clark has already answered while I was typing). Jonathan
Re: Lovefilm, yes or no?
On Wed, Apr 14, 2010 at 02:05:51PM +0100, Peter Edwards wrote: > Funniest interview question I heard of recently (not Lovefilm) was: > "What's two to the power 14" > As in, work out the answer there and then, not type in perl -e 'print > 2**14, "\n"' as eny fule kno 16384 (I admit that I did check that I can remember it correctly.) I'm starting to think that that's actually quite a good question really. Either they get it wrong Or they get it right, but use paper to work it out Or they get it right in their head and even for the third case, how fast they answer is useful. Did they just know it? Did they start from 65536 and halve twice? Or did it take more mental arithmetic than that. (Among other things, it's the address of the first byte of RAM on a ZX Spectrum) Nicholas Clark
Re: Lovefilm, yes or no?
On 14 April 2010 13:19, ian wrote: > There might be less comments to this thread if the people who have *not* > been tested and rejected leave a comment. > > However, as a matter of interest, the test I took was the 'pelmanism' game > (turning over cards to find a match). > > Has anyone been given a different test? > I know a couple of people not on this list, one who joined in the last 6 months and seems happy enough there, another who interviewed for a perm job a couple of weeks ago and didn't get it. You takes your pick... Funniest interview question I heard of recently (not Lovefilm) was: "What's two to the power 14" As in, work out the answer there and then, not type in perl -e 'print 2**14, "\n"' as eny fule kno Cheers, Peter
Re: Lovefilm, yes or no?
There might be less comments to this thread if the people who have *not* been tested and rejected leave a comment. However, as a matter of interest, the test I took was the 'pelmanism' game (turning over cards to find a match). Has anyone been given a different test? Regards Ian On 14/04/2010 11:50, Dominic Thoreau wrote: On 14 April 2010 11:24, Pinky Weaselly wrote: Sorry for anon email, but I don't want to announce to my employer that I've been approached by lovefilm about a job. The recruiter started with "if I said 'lovefilm', would you say 'no'?" Alarm bells are ringing. Can anyone say if they're a good employer, from a Perl perspective? You can email me privately if you like. I don't know what it's like to actually work for them - I did a phone interview, and their test (basically, write code fast, on deadline).[1] But they didn't hire me. After talking with previous colleagues (who are better perl devs than I am - and didn't get hired either) I get the opinion that they're trying to hire the elite - and almost to the point of being snobbish about it. As usual, YMMV Dominic [1] Without going into specifics of the task involved, they will ask you to nominate a time in the future. At that time, their system will arrange for an email to be delivered to you with a programming assignment, which you have one hour to complete and return.
Re: Lovefilm, yes or no?
On 14 Apr 2010, at 11:50, Dominic Thoreau wrote: > But they didn't hire me. After talking with previous colleagues (who > are better perl devs than I am - and didn't get hired either) I get > the opinion that they're trying to hire the elite - and almost to the > point of being snobbish about it. I also didn't get hired, but the impression I got was that they wanted people who were as good DBAs as they were Perl programmers. (My SQL wasn't up to scratch). The location is also a bit out of the way (over in Acton IIRC). -- David Dorward http://dorward.me.uk
Re: Lovefilm, yes or no?
On 14 April 2010 11:24, Pinky Weaselly wrote: > > Sorry for anon email, but I don't want to announce to my employer that I've > been approached by lovefilm about a job. > > The recruiter started with "if I said 'lovefilm', would you say 'no'?" > > Alarm bells are ringing. Can anyone say if they're a good employer, from a > Perl perspective? You can email me privately if you like. I don't know what it's like to actually work for them - I did a phone interview, and their test (basically, write code fast, on deadline).[1] But they didn't hire me. After talking with previous colleagues (who are better perl devs than I am - and didn't get hired either) I get the opinion that they're trying to hire the elite - and almost to the point of being snobbish about it. As usual, YMMV Dominic [1] Without going into specifics of the task involved, they will ask you to nominate a time in the future. At that time, their system will arrange for an email to be delivered to you with a programming assignment, which you have one hour to complete and return. -- Noli immiscere te draconum rebus nam fragilis es dentibus et cum garo bene sapis.
Lovefilm, yes or no?
Sorry for anon email, but I don't want to announce to my employer that I've been approached by lovefilm about a job. The recruiter started with "if I said 'lovefilm', would you say 'no'?" Alarm bells are ringing. Can anyone say if they're a good employer, from a Perl perspective? You can email me privately if you like. Pinky _ http://clk.atdmt.com/UKM/go/19780/direct/01/ We want to hear all your funny, exciting and crazy Hotmail stories. Tell us now
