49 lines
781 B
C++
49 lines
781 B
C++
/* Check cf5-opt.vim defs.
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VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
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VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
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*/
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#include <iostream>
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#include <vector>
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/*
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Summation of primes
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Problem 10
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The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
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Find the sum of all the primes below two million.
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Solution:
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142913828922
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*/
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typedef std::vector<long long> pt;
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pt p;
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bool isPrime( long long n )
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{
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long h = (long long)sqrt(double(n));
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for ( pt::iterator i = p.begin(), ie = p.end();
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i!=ie && *i<=h;
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++i )
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if ( !(n%*i) )
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return false;
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return true;
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}
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int main ( void )
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{
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const long long n = 2000000;
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long long s = 0;
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for ( long long i = 2; i < n; ++ i )
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if ( isPrime( i ) )
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{
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p.push_back( i );
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s+=i;
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}
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std::cout << s << std::endl;
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return 0;
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}
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