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  1. #include <omp.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. void parallel_prefix_sum(int *arr, int n) {
  6.     int *temp = (int *)malloc(n * sizeof(int));
  7.     if (!temp) {
  8.         printf("Memory allocation failed.\n");
  9.         return;
  10.     }
  11.  
  12.     // First phase: Perform a sequential scan in parallel
  13.     #pragma omp parallel for
  14.     for (int i = 0; i < n; i++) {
  15.         if (i == 0) {
  16.             temp[i] = arr[i];
  17.         } else {
  18.             temp[i] = arr[i] + temp[i - 1];
  19.         }
  20.     }
  21.  
  22.     // Copy the results back into arr
  23.     #pragma omp parallel for
  24.     for (int i = 0; i < n; i++) {
  25.         arr[i] = temp[i];
  26.     }
  27.  
  28.     free(temp);
  29. }
  30.  
  31. int main() {
  32.     int n = 10;
  33.     int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  34.  
  35.     printf("Original Array: ");
  36.     for (int i = 0; i < n; i++) {
  37.         printf("%d ", arr[i]);
  38.     }
  39.     printf("\n");
  40.  
  41.     parallel_prefix_sum(arr, n);
  42.  
  43.     printf("Prefix Sum Array: ");
  44.     for (int i = 0; i < n; i++) {
  45.         printf("%d ", arr[i]);
  46.     }
  47.     printf("\n");
  48.  
  49.     return 0;
  50. }
  51.  
Success #stdin #stdout 0s 5316KB
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stdin
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Standard input is empty
stdout
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Original Array: 1 2 3 4 5 6 7 8 9 10 
Prefix Sum Array: 1 3 6 10 15 21 28 36 45 55
https://ideone.com/FYkd3o
language:
C++14 (gcc 8.3)
created:
10 days ago
visibility:
public

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