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  1. #include <iostream>
  2. #include <vector>
  3. #include <thread>
  4. #include <mutex>
  5. #include <condition_variable>
  6.  
  7.  
  8. using namespace std;
  9.  
  10. int n;
  11. vector<vector<int> > D;
  12. int numberOfThreads = 4;
  13.  
  14. mutex m;
  15. condition_variable cv;
  16. int counter = 0;
  17.  
  18. void runThread(int x) {
  19. 	for (int k = 0; k < n; ++k) {
  20.  
  21. 		for (int i = x; i < n; i+= numberOfThreads) {
  22. 			for (int j = 0; j < n; ++j) {
  23. 				D[i][j] = min(D[i][j], D[i][k] + D[k][j]);
  24. 			}
  25. 		}
  26.  
  27. 		m.lock();
  28. 		counter++;
  29.  
  30. 		if(counter == numberOfThreads) {
  31. 			counter = 0;
  32. 			cv.notify_all();
  33. 		} else {
  34. 			unique_lock<std::mutex> lk(m);
  35. 			cv.wait(lk, [ ] { return counter == 0;});
  36. 		}
  37.  
  38. 		m.unlock();
  39.  
  40. 	}
  41. }  
  42.  
  43. int main() {
  44.   ios_base::sync_with_stdio(false);
  45.   cin.tie(nullptr);
  46.  
  47.   cin >> n;
  48.   D.assign(n, vector<int>(n));
  49.   vector<thread> myThreads(numberOfThreads);
  50.  
  51.   for (int i = 0; i < n; ++i)
  52.     for (int j = 0; j < n; ++j)
  53.       cin >> D[i][j];
  54.  
  55.   for(int i = 0; i < numberOfThreads; i++) {
  56. 	  myThreads[i] = thread(runThread, i);
  57.   }
  58.  
  59.     for(int i = 0; i < numberOfThreads; i++) {
  60. 	  myThreads[i].join();
  61.   }
  62.  
  63.   for (int i = 0; i < n; ++i) {
  64.     for (int j = 0; j < n; ++j) {
  65.       if (j > 0)
  66.         cout << ' ';
  67.       cout << D[i][j];
  68.     }
  69.     cout << endl;
  70.   }
  71. }
Success #stdin #stdout 0s 4408KB
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https://ideone.com/HaVubD
language:
C++14 (clang 8.0)
created:
4 years ago
visibility:
public

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