Poll & solutions

[elz]

First:

Poll #1689

Open to: Registered Users, detailed results viewable to: All, participants: 25

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Tickyboxes!

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Finished lecture 2
24 (96.0%)

Finished problem set 1
15 (60.0%)

Also, it occurs to me that it might be handy to have a place to post/discuss solutions to the problem sets, to see what we can learn from each other in the absence of TAs. If you actually go to MIT and the problem sets are still the same, don't read these. ;)

Fire away!

Comments

[elz]

Okay, here's my slept-on-it version, with bonus wisdom gleaned from ungemmed. I succeeded in getting rid of the stored boolean and made the initial variable assignments a little less hackish. Hopefully. :)

def find_nth_prime(prime_to_find):
    n = 1
    primes = []
    if prime_to_find < 1:
        print "Please enter a number greater than zero."
        return None
    else:
        while len(primes) < prime_to_find:
            if len(primes) == 0:
                primes.append(2)
                print "%i is prime number #%i" % (primes[0], len(primes))
            else:
                root = math.sqrt(n)
                for prime in primes:
                    if n%prime == 0:
                        break                
                    elif prime > root:
                        primes.append(n)
                        print "%i is prime number #%i" % (n, len(primes))
                        break
            n = n + 2
        return primes[prime_to_find - 1]