Author Topic: Project Euler  (Read 136742 times)

万精油

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Re: Project Euler
« Reply #60 on: 六月 19, 2008, 12:42:09 pm »
Congratulations to FZY and ID94 for making to the top (100% problem solved)!! Really impressive.

I am also in page one now.  I still have about 15 problems to go.

I plan to do one problem a week, but it seems they are posting new problems once a week. With this rate, I can never catch up. :(  I thought they used to post new problems once every two weeks.

idiot94

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Re: Project Euler
« Reply #61 on: 六月 21, 2008, 10:09:17 am »
Prof. W, FZY did more than 95% of the problems. The rest are done by the other friends of WXC. I did not do anything at all :D ... haha....
In general, the men of lower intelligence won out. Afraid of of their own shortcomings ... they boldly moved into action. Their enemies, ...  thought there was no need to take by action what they could win by their brains. Thucydides, History

fzy

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Re: Project Euler
« Reply #62 on: 六月 21, 2008, 10:29:17 am »
I did about 80% of the problems. In the beginning people were quite ensusiastic, and the problems were easier. I remember we became ranked in a very short time. At the end we also got a lot of help, when there is light at the end of the tunnel.

The recent problems are very good, particulously 195, 198, and this week's 199. Still it is difficult to get a higher ranking. timing seems always a problem.

万精油

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Re: Project Euler
« Reply #63 on: 六月 21, 2008, 10:52:43 am »
Quote
The recent problems are very good, particulously 195, 198, and this week's 199. Still it is difficult to get a higher ranking. timing seems always a problem.

I am back to my old routine, i.e. solve problem by their natural order. Thus, I haven't tried 198 and 199.

Yes, 195 is interesting. I did it because I "saw" a quick way to do it. Unfortunately, I missed the factor 3 problem and keep missing the upper bound, took me a while to catch the missing part. My final code was just one line different from my original code.

The timing for the new problem is good for Europe people (or west cost people), but not good for East cost people. My brain stop functioning after 1am (I know that because most of my losing WeiQi games on the internet are played after 1am :)).  It used to be the other way around. When I was young, my brain start up after 10pm. :(

« Last Edit: 六月 21, 2008, 10:55:17 am by 万精油 »

fzy

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Re: Project Euler
« Reply #64 on: 六月 26, 2008, 09:23:37 am »
Hi Professor,

Have you seen this news item on PE? Now you have time to catch up.

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Due to vacations that the team will be taking at various times during the summer (in the Northern hemisphere) we have made the slightly regrettable decision to suspend the release of weekly problems during July and August. We hope that you will appreciate how hard the team work to produce these problems that we all enjoy on a weekly basis and I think you will agree that a well earned rest is fully deserved.

But all is not bad news... incredible as it may sound, this Saturday, 28 June 2008, signifies the release of our 200th problem! In developing it we believe that it captures something for everyone: interest and challenge, as it is neither too hard nor too easy, and extra points for anyone able to spot the "200" connection. (c;

As an additional bonus you will be treated to TWO problems on 5 July before the break commences: one medium and one hard problem. Then we will return on 5/6 September with FIVE easy problems.

So enjoy the "200" problem and the following week's "double bill", and after that we trust you will have a restful summer.


万精油

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Re: Project Euler
« Reply #65 on: 六月 26, 2008, 11:25:31 am »
Quote
Have you seen this news item on PE? Now you have time to catch up.

This is indeed good news for me. I don't know how much I will catch up, since I myself have a busy summer schedule too (mostly fun and vacation stuff). At least, with PE break during the summer, I know I will not drag more behind. :)

Just solved 175. Got stuck with this seemingly "easy" problem for quite a while. :(

BTW, just saw PE's official language list, MATLAB is not one of them, too bad.

万精油

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Re: Project Euler
« Reply #66 on: 六月 30, 2008, 03:40:27 pm »
Really dissapointed. With such a big fuss, the No. 200 problem doesn't seem to be very interesting. I haven't solve that problem yet, but I think with a brute force search it should be doable. What I am dissapointed is that the problem lacks and "cleverness" or "educational" feature. It is more like a man-made problem not suitable for anything else. The only thing that it is special is there is a "200" in the problem (for the No. 200 problem). But, there are many other ways to connect 200 to a problem, such as find the 200th term of a sequence, etc.

After seeing this problem, my interest to PE took a big dive. I will still try to solve all the problems, but not as motivated as before.:(

万精油

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Re: Project Euler
« Reply #67 on: 七月 21, 2008, 09:33:20 am »
Finally solved Problem 167 (Ulam sequence) last weekend. I had the basic idea correct the first time around, but didn't expect the last period to be that big. Since my approach of generating Ulam sequence was slow. It is almost impossible to compute to 2 million terms in short time. Last weekend, I devised a faster way to compute Ulam sequence (not as fast as the ones I found after reading other people's solution), but my approach is universal, not bound to (2,2n+1) form.  I am glad this problem is gone. :(

fzy

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Re: Project Euler
« Reply #68 on: 七月 22, 2008, 10:10:12 am »
Finally solved Problem 167 (Ulam sequence) last weekend.

That is a nice problem though.

万精油

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Re: Project Euler
« Reply #69 on: 九月 29, 2008, 03:32:57 pm »
I finally had some time to get rid the last two problems on my waiting list. Problem 181 and problem 198. I think the hardest problem is 198 so far. I had the right idea of using continued fractions, but missed the trivial ones (those in the form of 1/(2*x); It costed me many days. Problem 181 is another matter. It is precision problem again (because the answer is more than 16 digits).

I haven't got the time to do the new problem yet (problem 210). I think the key is to figure out how many integer grid points in a given circle of a LARGE radius.

万精油

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Re: Project Euler
« Reply #70 on: 十月 04, 2008, 10:54:05 am »
Problem 210 is not hard, it is easy to figure out what to compute and how to compute it. However, since the answer is more 18 digits long, and many computations require precision in both end (sqrt need to know digits after decimal and square numbers need to know the 18th digits). Ordinary computation will not work. This seems to be the trend of Project of Euler now. You get the idea quickly but spend a lot of time to deal with the small nuance. Not worth it. I used to tell myself once I solved all problems before 200, I will quit. Now, I have solved more than that, finished all problems except the last two. It's time to quit.

I have learnt a lot in PE, a really interesting project.

Other people are still encouraged to discuss PE problem in this thread.

haha2000

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Re: Project Euler
« Reply #71 on: 十一月 12, 2008, 12:07:45 pm »
According to http://projecteuler.net/:

Who are the problems aimed at?

The intended audience include students for whom the basic curriculum is not feeding their hunger to learn, adults whose background was not primarily mathematics but had an interest in things mathematical, and professionals who want to keep their problem solving and mathematics on the edge.


I think many guys here may be not qualified, since you are well trained mathematicians + some computer scientists (such as Prof. Wan, FZY, IDIOT94)...

LOL...