Created
January 10, 2014 02:19
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The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million.
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| #We take the opposite approach here and find all the composite numbers | |
| # upto 2 million and then we sum what is not composite(prime). | |
| def prime(n): | |
| composite = range(n) | |
| for a in xrange(2, n): | |
| b = a | |
| for b in xrange(a * a, n, a): | |
| composite[b] = 0; | |
| sum = 0 | |
| for i in xrange(2, n): | |
| if composite[i] != 0: | |
| sum = sum + i | |
| return sum | |
| print prime(2000000) |
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