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  1. #include <iostream>  
  2. #include <vector>  
  3. #include <cmath>  
  4. #include <mpi.h>  
  5.  
  6. // Function to check if a number is prime  
  7. bool isPrime(int num) {
  8. 	if (num <= 1) return false;
  9. 	for (int i = 2; i <= sqrt(num); i++) {
  10. 		if (num % i == 0) return false;
  11. 	}
  12. 	return true;
  13. }
  14.  
  15. // Function to find the largest gap between consecutive prime numbers  
  16. int findLargestGap(int start, int end) {
  17. 	int largestGap = 0;
  18. 	int prevPrime = -1;
  19. 	for (int i = start; i <= end; i++) {
  20. 		if (isPrime(i)) {
  21. 			if (prevPrime != -1) {
  22. 				largestGap = std::max(largestGap, i - prevPrime);
  23. 			}
  24. 			prevPrime = i;
  25. 		}
  26. 	}
  27. 	return largestGap;
  28. }
  29.  
  30. int main(int argc, char** argv) {
  31. 	MPI_Init(&argc, &argv);
  32.  
  33. 	int rank, size;
  34. 	MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  35. 	MPI_Comm_size(MPI_COMM_WORLD, &size);
  36.  
  37. 	int n;
  38. 	if (rank == 0) {
  39. 		std::cout << "Enter the value of n: ";
  40. 		std::cin >> n;
  41. 	}
  42.  
  43. 	MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
  44.  
  45. 	int chunkSize = n / size;
  46. 	int start = rank * chunkSize + 2; // Start from 2, the first prime number  
  47. 	int end = (rank == size - 1) ? n : (start + chunkSize - 1);
  48.  
  49. 	double startTime = MPI_Wtime();
  50. 	int largestGap = findLargestGap(start, end);
  51. 	double endTime = MPI_Wtime();
  52.  
  53. 	int globalLargestGap;
  54. 	MPI_Reduce(&largestGap, &globalLargestGap, 1, MPI_INT, MPI_MAX, 0, MPI_COMM_WORLD);
  55.  
  56. 	double timeTaken = endTime - startTime;
  57. 	double totalTimeTaken;
  58. 	MPI_Reduce(&timeTaken, &totalTimeTaken, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
  59.  
  60. 	if (rank == 0) {
  61. 		std::cout << "Largest gap between consecutive prime numbers less than " << n << ": " << globalLargestGap << std::endl;
  62. 		std::cout << "Time taken: " << totalTimeTaken << " seconds" << std::endl;
  63. 	}
  64.  
  65. 	MPI_Finalize();
  66. 	return 0;
  67. }
  68.  
Success #stdin #stdout #stderr 0.31s 40396KB
comments (?)
stdin
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n=100000
stdout
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Standard output is empty
stderr
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Error: unexpected '/' in "/"
Execution halted
https://ideone.com/zuj4Ng
language:
R (R 3.5.2)
created:
16 hours ago
visibility:
public

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