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  1. #include <iostream>
  2. #include <vector>
  3. #include <cstdlib>
  4. #include <ctime>
  5. #include <omp.h>
  6.  
  7. #define N 5  // Set a small value (e.g., N=5) for readable output
  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 print a matrix
  21. void printMatrix(const vector<vector<int>>& matrix, const string& name) {
  22.     cout << name << " Matrix:\n";
  23.     for (int i = 0; i < N; i++) {
  24.         for (int j = 0; j < N; j++) {
  25.             cout << matrix[i][j] << " ";
  26.         }
  27.         cout << endl;
  28.     }
  29.     cout << endl;
  30. }
  31.  
  32. // Function to multiply matrices using OpenMP
  33. void multiplyMatrices(const vector<vector<int>>& A, const vector<vector<int>>& B, vector<vector<int>>& C) {
  34.     #pragma omp parallel for collapse(2)
  35.     for (int i = 0; i < N; i++) {
  36.         for (int j = 0; j < N; j++) {
  37.             C[i][j] = 0;
  38.             for (int k = 0; k < N; k++) {
  39.                 C[i][j] += A[i][k] * B[k][j];
  40.             }
  41.         }
  42.     }
  43. }
  44.  
  45. int main() {
  46.     srand(time(0));
  47.  
  48.     vector<vector<int>> A(N, vector<int>(N));
  49.     vector<vector<int>> B(N, vector<int>(N));
  50.     vector<vector<int>> C(N, vector<int>(N, 0));
  51.  
  52.     generateMatrix(A);
  53.     generateMatrix(B);
  54.  
  55.     if (N <= 10) {  // Print only if N is small to avoid large output
  56.         printMatrix(A, "A");
  57.         printMatrix(B, "B");
  58.     }
  59.  
  60.     clock_t start = clock(); // Use clock() instead of omp_get_wtime()
  61.  
  62.     multiplyMatrices(A, B, C);
  63.  
  64.     clock_t end = clock(); // End time
  65.  
  66.     if (N <= 10) {  // Print result matrix only if N is small
  67.         printMatrix(C, "C");
  68.     }
  69.  
  70.     double time_taken = double(end - start) / CLOCKS_PER_SEC;
  71.     cout << "Matrix multiplication completed in " << time_taken << " seconds." << endl;
  72.  
  73.     return 0;
  74. }
  75.  
Success #stdin #stdout 0.01s 5284KB
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stdin
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Standard input is empty
stdout
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A Matrix:
9 1 9 1 4 
1 8 2 8 6 
9 0 2 2 0 
9 0 3 7 5 
4 7 8 6 9 

B Matrix:
3 3 6 4 4 
8 3 5 7 6 
1 0 5 6 0 
3 5 1 5 7 
1 6 7 4 5 

C Matrix:
51 59 133 118 69 
99 103 106 136 138 
35 37 66 58 50 
56 92 111 109 110 
103 117 168 179 145 

Matrix multiplication completed in 0 seconds.
https://ideone.com/CdJJSR
language:
C++ (gcc 8.3)
created:
3 hours ago
visibility:
public

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