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Problem 1761. Primes Faster for Large N

Solution 480841

Submitted on 30 Jul 2014 by rifat
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Test Suite

Test Status Code Input and Output
1   Pass
feval(@assignin,'caller','score',30); %

2   Pass
%% tic assert(isequal(primes_faster(1),primes(1))) assert(isequal(primes_faster(2),primes(2))) for i=1:100 n=randi(2000,1); assert(isequal(primes_faster(n),primes(n))) end toc

Elapsed time is 0.032166 seconds.

3   Pass
%% tic ta=clock; p = primes_faster(2^28); t1=etime(clock,ta); % time in sec fprintf('P 2^28 %12i %10.3f\n',length(p),t1) assert(isequal(size(unique(p),2),14630843)) ptr=randi(7603553,1,10); % small to avoid timeout pchk=double(p(ptr)); assert(all(isprime(pchk))) feval( @assignin,'caller','score',floor(min(30,t1)) ); toc

P 2^28 14630843 7.177 Elapsed time is 8.167072 seconds.

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