OpenMP Sections

par.c

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+/* C implementation QuickSort from  http://w...content-available-to-author-only...s.org/quick-sort/ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <omp.h>
+
+// A utility function to swap two elements
+void swap(int *a, int *b)
+{
+    int t = *a;
+    *a = *b;
+    *b = t;
+}
+
+/* This function takes last element as pivot, places
+   the pivot element at its correct position in sorted
+    array, and places all smaller (smaller than pivot)
+   to left of pivot and all greater elements to right
+   of pivot */
+int partition(int arr[], int low, int high)
+{
+    int pivot = arr[high]; // pivot
+    int i = (low - 1);     // Index of smaller element
+
+    for (int j = low; j <= high - 1; j++)
+    {
+        // If current element is smaller than or
+        // equal to pivot
+        if (arr[j] <= pivot)
+        {
+            i++; // increment index of smaller element
+            swap(&arr[i], &arr[j]);
+        }
+    }
+
+    swap(&arr[i + 1], &arr[high]);
+
+    return (i + 1);
+}
+
+/* The main function that implements QuickSort
+ arr[] --> Array to be sorted,
+  low  --> Starting index,
+  high  --> Ending index */
+void quickSort(int arr[], int low, int high)
+{
+    if (low < high)
+    {
+        /* pi is partitioning index, arr[p] is now
+       at right place */
+        int pi = partition(arr, low, high);
+
+        // Separately sort elements before
+        // partition and after partition
+#pragma omp parallel sections
+        {
+#pragma omp section
+            quickSort(arr, low, pi - 1);
+#pragma omp section
+            quickSort(arr, pi + 1, high);
+        }
+    }
+}
+
+/* Function to print an array */
+void printArray(int arr[], int size)
+{
+    int i;
+
+    for (i = 0; i < size; i++)
+    {
+        printf("%d ", arr[i]);
+    }
+
+    printf("\n");
+}
+
+// Driver program to test above functions
+int main()
+{
+    int i, n = 10000000;
+    int *arr = (int *)malloc(n * sizeof(int));
+
+    for (i = 0; i < n; i++)
+    {
+        arr[i] = rand() % n;
+    }
+
+    quickSort(arr, 0, n - 1);
+    //printf("Sorted array: \n");
+    //printArray(arr, n);
+    return 0;
+}