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  1. #include <iostream>
  2. #include <vector>
  3. #include <cstdlib>
  4. #include <ctime>
  5. #include <omp.h>
  6.  
  7. #define N 500  // Define matrix size
  8.  
  9. using namespace std;
  10.  
  11. // Function to generate a random matrix
  12. void generateMatrix(vector<vector<int>>& matrix) {
  13.     for (int i = 0; i < N; i++) {
  14.         for (int j = 0; j < N; j++) {
  15.             matrix[i][j] = rand() % 10;  // Random values from 0 to 9
  16.         }
  17.     }
  18. }
  19.  
  20. // Function to multiply matrices using OpenMP
  21. void multiplyMatrices(const vector<vector<int>>& A, const vector<vector<int>>& B, vector<vector<int>>& C) {
  22.     #pragma omp parallel for collapse(2)
  23.     for (int i = 0; i < N; i++) {
  24.         for (int j = 0; j < N; j++) {
  25.             C[i][j] = 0;
  26.             for (int k = 0; k < N; k++) {
  27.                 C[i][j] += A[i][k] * B[k][j];
  28.             }
  29.         }
  30.     }
  31. }
  32.  
  33. int main() {
  34.     srand(time(0));
  35.  
  36.     vector<vector<int>> A(N, vector<int>(N));
  37.     vector<vector<int>> B(N, vector<int>(N));
  38.     vector<vector<int>> C(N, vector<int>(N, 0));
  39.  
  40.     generateMatrix(A);
  41.     generateMatrix(B);
  42.  
  43.     clock_t start = clock(); // Use clock() instead of omp_get_wtime()
  44.  
  45.     multiplyMatrices(A, B, C);
  46.  
  47.     clock_t end = clock(); // End time
  48.  
  49.     double time_taken = double(end - start) / CLOCKS_PER_SEC;
  50.     cout << "Matrix multiplication completed in " << time_taken << " seconds." << endl;
  51.  
  52.     return 0;
  53. }
  54.  
Success #stdin #stdout 0.28s 6600KB
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Standard input is empty
stdout
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Matrix multiplication completed in 0.25722 seconds.
https://ideone.com/YPgHAw
language:
C++ (gcc 8.3)
created:
3 hours ago
visibility:
public

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