The file to test threading on

main.cpp

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+#include <iostream>
+#include <vector>
+#include <chrono>
+#include <algorithm>
+#include <thread>
+#include <fstream>
+#define ARR_LEN 45'000
+using namespace std;
+
+void merge(int array[], int const left, int const mid,
+           int const right)
+{
+    int const subArrayOne = mid - left + 1;
+    int const subArrayTwo = right - mid;
+
+    // Create temp arrays
+    auto *leftArray = new int[subArrayOne],
+            *rightArray = new int[subArrayTwo];
+
+    // Copy data to temp arrays leftArray[] and rightArray[]
+    for (auto i = 0; i < subArrayOne; i++)
+        leftArray[i] = array[left + i];
+    for (auto j = 0; j < subArrayTwo; j++)
+        rightArray[j] = array[mid + 1 + j];
+
+    auto indexOfSubArrayOne = 0, indexOfSubArrayTwo = 0;
+    int indexOfMergedArray = left;
+
+    // Merge the temp arrays back into array[left..right]
+    while (indexOfSubArrayOne < subArrayOne
+           && indexOfSubArrayTwo < subArrayTwo) {
+        if (leftArray[indexOfSubArrayOne]
+            <= rightArray[indexOfSubArrayTwo]) {
+            array[indexOfMergedArray]
+                    = leftArray[indexOfSubArrayOne];
+            indexOfSubArrayOne++;
+        }
+        else {
+            array[indexOfMergedArray]
+                    = rightArray[indexOfSubArrayTwo];
+            indexOfSubArrayTwo++;
+        }
+        indexOfMergedArray++;
+    }
+
+    // Copy the remaining elements of
+    // left[], if there are any
+    while (indexOfSubArrayOne < subArrayOne) {
+        array[indexOfMergedArray]
+                = leftArray[indexOfSubArrayOne];
+        indexOfSubArrayOne++;
+        indexOfMergedArray++;
+    }
+
+    // Copy the remaining elements of
+    // right[], if there are any
+    while (indexOfSubArrayTwo < subArrayTwo) {
+        array[indexOfMergedArray]
+                = rightArray[indexOfSubArrayTwo];
+        indexOfSubArrayTwo++;
+        indexOfMergedArray++;
+    }
+    delete[] leftArray;
+    delete[] rightArray;
+}
+
+// begin is for left index and end is right index
+// of the sub-array of arr to be sorted
+void mergeSort(int array[], int const begin, int const end)
+{
+    if (begin >= end)
+        return;
+
+    int mid = begin + (end - begin) / 2;
+    mergeSort(array, begin, mid);
+    mergeSort(array, mid + 1, end);
+    merge(array, begin, mid, end);
+}
+
+void bubbleSort(int arr[], int n)
+{
+    int i, j;
+    bool swapped;
+    for (i = 0; i < n - 1; i++) {
+        swapped = false;
+        for (j = 0; j < n - i - 1; j++) {
+            if (arr[j] > arr[j + 1]) {
+                swap(arr[j], arr[j + 1]);
+                swapped = true;
+            }
+        }
+
+        // If no two elements were swapped
+        // by inner loop, then break
+        if (!swapped)
+            break;
+    }
+}
+
+int main() {
+    using std::chrono::high_resolution_clock;
+    using std::chrono::duration_cast;
+    using std::chrono::duration;
+    using std::chrono::milliseconds;
+    srand(time(nullptr));
+
+
+    int nums1[ARR_LEN];
+    int (*p1)[ARR_LEN] = &nums1;
+    int nums2[ARR_LEN];
+
+    for(int & i : nums1) {
+        i = (int) rand() % 750 + 1;
+    }
+
+    copy(nums1, nums1+ARR_LEN, nums2);
+
+    auto total1 = high_resolution_clock ::now();
+
+    auto t1 = high_resolution_clock::now();
+    bubbleSort(nums1, ARR_LEN);
+//    mergeSort(nums1, 0, sizeof(nums1) / sizeof(nums1[0]));
+//    thread merge (mergeSort, nums1, 0, sizeof(nums1) / sizeof(nums1[0]));
+    auto t2 = high_resolution_clock::now();
+
+
+    auto t3 = high_resolution_clock ::now();
+    bubbleSort(nums2, ARR_LEN);
+//    thread bubble (bubbleSort, nums2, ARR_LEN);
+    auto t4 = high_resolution_clock ::now();
+
+//    thread bubble2(bubbleSort, nums1, 0);
+
+
+//    bubble2.join();
+//    bubble.join();
+    auto total2 = high_resolution_clock::now();
+
+    auto ms1 = duration<double, std::milli>(t2-t1);
+    auto ms2 = duration<double, std::milli>(t4-t3);
+    auto total_time = duration<double, std::milli>(total2-total1);
+    cout << "Merge sort took: "<< ms1.count() << "ms" << endl;
+    cout << "Bubble sort took: " << ms2.count() << "ms" << endl;
+    cout << "Total time: " << total_time.count() << "ms" << endl;
+
+    return 0;
+}
+
+