#include <taskflow/taskflow.hpp>

int spawn(int n, tf::Subflow& sbf) {

if (n < 2) return n;

int res1, res2;

// compute f(n-1)

sbf.emplace([&res1, n] (tf::Subflow& sbf) { res1 = spawn(n - 1, sbf); } )

.name(std::to_string(n-1));

// compute f(n-2)

sbf.emplace([&res2, n] (tf::Subflow& sbf) { res2 = spawn(n - 2, sbf); } )

.name(std::to_string(n-2));

sbf.join();

return res1 + res2;

}

int main(int argc, char* argv[]) {

if(argc != 2) {

std::cerr << "usage: ./fibonacci N\n";

std::exit(EXIT_FAILURE);

}

int N = std::atoi(argv[1]);

if(N < 0) {

throw std::runtime_error("N must be non-negative");

}

int res; // result

tf::Executor executor;

tf::Taskflow taskflow("fibonacci");

taskflow.emplace([&res, N] (tf::Subflow& sbf) {

res = spawn(N, sbf);

}).name(std::to_string(N));

executor.run(taskflow).wait();

//taskflow.dump(std::cout);

std::cout << "Fib[" << N << "]: " << res << std::endl;

return 0;

}