cpp17.palgorithms.org

Parallel Algorithms

Supported Algorithm

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C++17 in details: Parallel Algorithms

http://www.modernescpp.com/index.php/parallel-algorithm-of-the-standard-template-library

Execution policies

The execution policy parameter will tell the algorithm how it should be executed. We have the following options:

sequenced_policy - is an execution policy type used as a unique type to disambiguate parallel algorithm overloading and require that a parallel algorithm’s execution may not be parallelized. the corresponding global object is std::execution::seq parallel_policy - is an execution policy type used as a unique type to disambiguate parallel algorithm overloading and indicate that a parallel algorithm’s execution may be parallelized. the corresponding global object is std::execution::par parallel_unsequenced_policy - is an execution policy type used as a unique type to disambiguate parallel algorithm overloading and indicate that a parallel algorithm’s execution may be parallelized and vectorized. the corresponding global object is std::execution::par_unseq

text extracted from: https://www.bfilipek.com/2017/08/cpp17-details-parallel.html

source code based from: https://stackoverflow.com/questions/21516575/fill-a-vector-with-random-numbers-c

#include <iostream>
#include <functional>
#include <algorithm>
#include <random>
#include <execution>

using namespace std;

void print(const vector<int>& vec)
{
	for( auto& i: vec)
	{
		cout << i << " ";
	}
	cout << endl;
}

int main()
{
	random_device rnd_device;
	mt19937 mersenne_engine {rnd_device()};
	uniform_int_distribution <int> dist {1, 52};
	
	auto gen = [&dist, &mersenne_engine](){ return dist(mersenne_engine);};
	
	vector<int> vec(100);
	std::generate(begin(vec), end(vec), gen);
	print(vec);
	
	cout << "standard sort" << endl;
	std::sort(vec.begin(), vec.end());
	print(vec);
	
	std::shuffle(begin(vec), end(vec), mersenne_engine);
	
	cout << "Sequential sort" << endl;
	std::sort(std::execution::seq, vec.begin(), vec.end());
	print(vec);
	
	std::shuffle(begin(vec), end(vec), mersenne_engine);	
	cout << "Permiting parallel execution sort" << endl;
	std::sort(std::execution::par, vec.begin(), vec.end());
	print(vec);
	
	std::shuffle(begin(vec), end(vec), mersenne_engine);	
	cout << "Permiting parallel and vectorization execution sort" << endl;
	std::sort(std::execution::par_unseq, vec.begin(), vec.end());
	print(vec);
	
	return 0;
}