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KidDynamite posted:So I'm in school at Rutgers just finished Computers and Programming 101. I'm taking 102 in the fall, and then Computer Orginization and Data Structures & Algorithm Design. I'm doing Udacity(currently doing their 101) to supplement my learning and trying my hand at Project Euler(currently stuck on #3). Will this be enough to start applying for internships for next summer? Doing problem 3 in the obvious way gets me the answer in under a second. I'm not trying to be mean, but I really think you should work on your programming (or math?) skills before thinking about applying to internships. Problem 3 is not a hard problem. I literally started learning to program 2 days ago and I got it in under 5 minutes, and most of that time was spent looking up syntax.
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Jul 12, 2012 21:05
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| # ¿ Apr 29, 2024 07:36 |
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KidDynamite posted:I got something quickly too I just can't get my implementation to run in under a minute. If you're trying to factor a number n, you only need to test factors up to sqrt(n). You can find the rest based on those. You can also just test the odds on this one. If those don't help, post the code. My implementation in Haskell takes less than a second, so there's probably something really inefficient and easy to fix.
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Jul 12, 2012 23:29
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The reason it hangs is that your for-loop goes through 600851475141 iterations. Note that the factors of a number N are symmetrical about the square root of that number, in the sense that if K is a factor less than the square root, then N/K is a factor greater than the square root (do you see why?). One way to do it is to find all of the factors less than sqrt(600851475143), find the corresponding factor greater than the square root, and then check to see which of the factors are prime. This way is approximately 800,000 times more efficient (why?). EDIT: Also I think it would be more efficient to see if the number divides 600851475143 first and then see if it is prime, instead of the other way around, as you have it. Fewer divisions that way. Also, what the poster below said. buttcoin smuggler fucked around with this message at 01:55 on Jul 13, 2012 |
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Jul 13, 2012 01:50
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Yeah, sorry I missed that (I don't know anything about object oriented languages). Why can't you just write a method or function or whatever you call it instead of creating hundreds of thousands of objects?
buttcoin smuggler fucked around with this message at 02:03 on Jul 13, 2012 |
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Jul 13, 2012 01:58
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Null Pointer posted:You're about 12 orders of magnitude off. I don't know C++, but doesn't code:buttcoin smuggler fucked around with this message at 05:28 on Jul 13, 2012 |
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Jul 13, 2012 04:45
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Bongo Bill posted:LaTeX is easy to use and looks great. I'd highly recommend it. Just want to reiterate this. It makes all of my word processing easier (using Mendeley and bibtex alone saved me a lot of time in school). It's also far more elegant than Word.
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Aug 18, 2012 08:51
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