Heap Sort

Language: C++

#include <iostream>
#include <vector>
using namespace std;

void heapify(vector<int>& arr, int n, int i) {
    int largest = i;
    int left = 2 * i + 1;
    int right = 2 * i + 2;

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

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

    if (largest != i) {
        swap(arr[i], arr[largest]);
        heapify(arr, n, largest);
    }
}

void heapSort(vector<int>& arr) {
    int n = arr.size();

    // Build heap (rearrange array)
    for (int i = n / 2 - 1; i >= 0; i--)
        heapify(arr, n, i);

    // Extract elements from the heap one by one
    for (int i = n - 1; i > 0; i--) {
        swap(arr[0], arr[i]); // Move current root to end
        heapify(arr, i, 0); // Call max heapify on the reduced heap
    }
}

void printArray(const vector<<int>& arr) {
    for (int i : arr) {
        cout << i << " ";
    }
    cout << endl;
}

int main() {
    vector arr = {12, 11, 13, 5, 6, 7};
    
    cout << "Original array: ";
    printArray(arr);

    heapSort(arr);

    cout << "Sorted array: ";
    printArray(arr);

    return 0;
}

Output:

Original array: 12 11 13 5 6 7
Sorted array: 5 6 7 11 12 13