IndexSortThreading.cpp

#include <iostream>
#include <vector>
#include <thread>
#include <chrono>
#include <algorithm>

using namespace std;
using namespace std::chrono;

int SIZE = 10;

void indexSort(int arr[], int n) {
    int index[n];
    for (int i = 0; i < n; ++i) index[i] = i;

    for(int i=0;i < n;i++) {
        for(int j=i+1;j < n;j++) {
            if(arr[index[i]] > arr[index[j]]) {
                int temp = index[i];
                index[i] = index[j];
                index[j] = temp;
            }
        }
    }

    vector<int> v;
    for (int i = 0; i < n; ++i) {
        v.push_back(arr[index[i]]);
    }

    for (int i = 0; i < n; ++i) arr[i] = v[i];
}


void printArray(vector<int>& array);
void printArray(int *array, int sz);

void mergeArrays(int arr1[], int arr2[], int n1,
                 int n2, int arr3[]);


int main() {
    vector<int> a(SIZE);
    int* leftArray = (int *)malloc((SIZE/2+1) * sizeof(int));
    int* rightArray = (int *)malloc((SIZE/2+1) * sizeof(int));

    for (int m = 0; m < SIZE; m++) {
        a[m] = rand()%10;
    }

    for (int i = 0; i < SIZE/2; ++i) leftArray[i] = a[i];
    for (int i = 0, j = SIZE/2; i < SIZE/2; ++i, j++) {
        rightArray[i] = a[j];
    }

    thread t1 (indexSort, leftArray, SIZE/2);
    thread t2 (indexSort, rightArray, SIZE/2);

    t1.join();
    t2.join();

    int sortedArray[SIZE];
    mergeArrays(leftArray, rightArray, SIZE/2, SIZE/2, sortedArray);

//    printArray(leftArray, SIZE/2);
//    printArray(rightArray, SIZE/2);


    printArray(a);
    printArray(sortedArray, SIZE);
    cout << endl;
    return 0;
}

void printArray(vector<int>& array){
    for (int i = 0; i < SIZE; ++i) cout << array[i] << ' ';
    cout << endl;
}

void printArray(int *array, int sz){
    for (int i = 0; i < sz; ++i) cout << array[i] << ' ';
    cout << endl;
}

void mergeArrays(int arr1[], int arr2[], int n1,
                 int n2, int arr3[]) {
    int i = 0, j = 0, k = 0;
    while (i<n1 && j <n2) {
        if (arr1[i] < arr2[j])
            arr3[k++] = arr1[i++];
        else
            arr3[k++] = arr2[j++];
    }

    while (i < n1)
        arr3[k++] = arr1[i++];

    while (j < n2)
        arr3[k++] = arr2[j++];
}