Operating-System/sorting.cpp at main · Avisheet/Operating-System · GitHub

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// C++ program for Merge Sort
#include <bits/stdc++.h>
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;

    auto *leftArray = new int[subArrayOne],
         *rightArray = new int[subArrayTwo];

    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;

    while (indexOfSubArrayOne < subArrayOne
           && indexOfSubArrayTwo < subArrayTwo) {
        if (leftArray[indexOfSubArrayOne]
            <= rightArray[indexOfSubArrayTwo]) {
            array[indexOfMergedArray]
                = leftArray[indexOfSubArrayOne];
            indexOfSubArrayOne++;
        }

        else {
            array[indexOfMergedArray]
                = rightArray[indexOfSubArrayTwo];
            indexOfSubArrayTwo++;
        }
        indexOfMergedArray++;
    }

    while (indexOfSubArrayOne < subArrayOne) {
        array[indexOfMergedArray]
            = leftArray[indexOfSubArrayOne];
        indexOfSubArrayOne++;
        indexOfMergedArray++;
    }

    while (indexOfSubArrayTwo < subArrayTwo) {
        array[indexOfMergedArray]
            = rightArray[indexOfSubArrayTwo];
        indexOfSubArrayTwo++;
        indexOfMergedArray++;
    }
    delete[] leftArray;
    delete[] rightArray;
}

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 printArray(int A[], int size)
{
    for (int i = 0; i < size; i++)
        cout << A[i] << " ";
    cout << endl;
}

int main()
{
    int arr[] = { 12, 11, 13, 5, 6, 7 };
    int arr_size = sizeof(arr) / sizeof(arr[0]);

    cout << "Given array is \n";
    printArray(arr, arr_size);

    mergeSort(arr, 0, arr_size - 1);

    cout << "\nSorted array is \n";
    printArray(arr, arr_size);
    return 0;
}

// Heap sort
// #include <iostream>
// using namespace std;
void heapify(int arr[], int n, int i)
{
	int largest = i; // Initialize largest as root Since we are using 0 based indexing
	int l = 2 * i + 1; // left = 2*i + 1
	int r = 2 * i + 2; // right = 2*i + 2

	if (l < n && arr[l] > arr[largest])
		largest = l;

	if (r < n && arr[r] > arr[largest])
		largest = r;
	if (largest != i) {
		swap(arr[i], arr[largest]);
		heapify(arr, n, largest);
	}
}
void heapSort(int arr[], int n)
{
	for (int i = n / 2 - 1; i >= 0; i--)
		heapify(arr, n, i);
	for (int i = n - 1; i >= 0; i--) {
		swap(arr[0], arr[i]);
		heapify(arr, i, 0);
	}
}

void printArray(int arr[], int n)
{
	for (int i = 0; i < n; ++i)
		cout << arr[i] << " ";
	cout << "\n";
}
// int main()
// {
// 	int arr[] = { 60 ,20 ,40 ,70, 30, 10};
// 	int n = sizeof(arr) / sizeof(arr[0]);
// 	for(int i=n/2 -1;i>=0;i--){
// 	heapify(arr,n,i);
// }

// cout << "After heapifying array is \n";
// 	printArray(arr, n);


// 	heapSort(arr, n);

// 	cout << "Sorted array is \n";
// 	printArray(arr, n);

// return 0;
// }