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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 0.33s 40288KB
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Error: unexpected '/' in "/"
Execution halted
https://ideone.com/TY8gEZ
language:
R (R 3.5.2)
created:
16 hours ago
visibility:
public

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