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  1. #include <iostream>
  2. #include <future>
  3. #include <numeric>
  4. #include <vector>
  5. #include <list>
  6.  
  7. template <typename It, typename Func>
  8. void map(It first, It last, Func f)
  9. {
  10.     while (first != last)
  11.     {
  12.         f(*first++);
  13.     }
  14. }
  15.  
  16. template <typename It, typename MapFunc, typename FoldFunc>
  17. auto map_reduce(It first, It last, MapFunc f1, FoldFunc f2, size_t num_threads)
  18.     -> decltype(f2(f1(*first), f1(*first)))
  19. {
  20.     size_t block_size = std::distance(first, last) / num_threads;
  21.  
  22.     std::vector<std::future<void>> results(num_threads);
  23.     for (size_t i = 0; i < num_threads; ++i)
  24.     {
  25.         results[i] = std::async(map<It,decltype(f1)>, first, last, f1);
  26.     }
  27.  
  28.     return 0;
  29. }
  30.  
  31.  
  32. int main()
  33. {
  34.     std::list<int> ls = { 1, 2, 3 };
  35.     auto sum = map_reduce(ls.begin(), ls.end(),
  36.         [](int i) {return i; },
  37.         std::plus<int>(),
  38.         3);
  39.  
  40.     return 0;
  41. }
  42.  
  43.  
Success #stdin #stdout 0s 21408KB
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https://ideone.com/Epq7vc
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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