Project Euler Problem 10 – Sum for primes to 2 million
At first I attempted to solve this using the sieve code I wrote for problem 3. However that code used Python lists and was removing elements as it progressed. That was horribly inefficient. So I’ve learnt to use Python arrays, which I was surprised to learn are not a native data structure in Python. Anyway, for my reference here is the code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | import mathfrom array import arraydef getprimes(input): myarray = array('L',range(input)) myarray[1] = 0 for n in myarray: if n != 0: for j in xrange(n+n,int(input),n): myarray[j] = 0 retvals = [] for n in myarray: if n != 0: retvals.append(n) return retvalsp = getprimes(2000000)sum = 0for i in p: sum += iprint sum |
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