LP5 HPC Assignment 2B (1).cpp

//Cedrick Andrade
//COBA006

#include <iostream>
#include <vector>
#include <omp.h>

using namespace std;

void merge(vector<int>& arr, int left, int middle, int right) {
    int i, j, k;
    int n1 = middle - left + 1;
    int n2 = right - middle;
 
    vector<int> L(n1), R(n2);
 
    for (i = 0; i < n1; i++)
        L[i] = arr[left + i];
    for (j = 0; j < n2; j++)
        R[j] = arr[middle + 1 + j];
 
    i = 0;
    j = 0;
    k = left;
    while (i < n1 && j < n2) {
        if (L[i] <= R[j]) {
            arr[k] = L[i];
            i++;
        }
        else {
            arr[k] = R[j];
            j++;
        }
        k++;
    }
 
    while (i < n1) {
        arr[k] = L[i];
        i++;
        k++;
    }
 
    while (j < n2) {
        arr[k] = R[j];
        j++;
        k++;
    }
}
 
void mergeSort(vector<int>& arr, int left, int right) {
    if (left >= right) {
        return;
    }

    int middle = left + (right - left) / 2;

    #pragma omp parallel sections num_threads(2)
    {
        #pragma omp section
        {
            mergeSort(arr, left, middle);
        }

        #pragma omp section
        {
            mergeSort(arr, middle + 1, right);
        }
    }

    merge(arr, left, middle, right);
}

int main() {
    vector<int> arr = { 12, 11, 13, 5, 6, 7 };
    int n = arr.size();
 
    mergeSort(arr, 0, n - 1);
 
    cout << "Sorted array: ";
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";
    cout << endl;
 
    return 0;
}