lisa.pizzo/LisaPizzoExercises
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Delete mayer_primes.h

Browse source
This commit is contained in:
Lisa Pizzo 2025-10-29 18:19:25 +01:00
commit b05447a908
1 changed files with 0 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

73
mayer_primes.h
View file

@ -1,73 +0,0 @@
#pragma once
#include <cstring> //memset
#include <vector>
//using namespace std;
/** \brief Determines all prime numbers in interval [2, @p max].
*
* The sieve of Eratosthenes is used.
*
* The implementation originates from <a href="http://code.activestate.com/recipes/576559-fast-prime-generator/">Florian Mayer</a>.
*
* \param[in] max end of interval for the prime number search.
* \return vector of prime numbers @f$2,3,5, ..., p<=max @f$.
*
* \copyright
* Copyright (c) 2008 Florian Mayer (adapted by Gundolf Haase 2018)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
template <class T>
std::vector<T> get_primes(T max)
{
std::vector<T> primes;
char *sieve;
sieve = new char[max / 8 + 1];
// Fill sieve with 1
memset(sieve, 0xFF, (max / 8 + 1) * sizeof(char));
for (T x = 2; x <= max; x++)
{
if (sieve[x / 8] & (0x01 << (x % 8))) {
primes.push_back(x);
// Is prime. Mark multiplicates.
for (T j = 2 * x; j <= max; j += x)
{
sieve[j / 8] &= ~(0x01 << (j % 8));
}
}
}
delete[] sieve;
return primes;
}
//---------------------------------------------------------------
//int main() // by Florian Mayer
//{g++ -O3 -std=c++14 -fopenmp main.cpp && ./a.out
// vector<unsigned long> primes;
// primes = get_primes(10000000);
// // return 0;
// // Print out result.
// vector<unsigned long>::iterator it;
// for(it=primes.begin(); it < primes.end(); it++)
// cout << *it << " ";
//
// cout << endl;
// return 0;
//}