2. Constructing the heap for the list 11, 51, 42, 35, 23, 45, 32 a. Bottom-up b. Top-down c. Array representation and sort it (write out the steps in both of the two stages.) code example

Example 1: Heap sort in c++

#include <iostream>
 
using namespace std;
 

void heapify(int arr[], int n, int i)
{
    int largest = i; 
    int l = 2 * i + 1;
    int r = 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[] = { 12, 11, 13, 5, 6, 7 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    heapSort(arr, n);
 
    cout << "Sorted array is \n";
    printArray(arr, n);
}

Example 2: heap sort

// @see https://www.youtube.com/watch?v=H5kAcmGOn4Q

function heapify(list, size, index) {
    let largest = index;
    let left = index * 2 + 1;
    let right = left + 1;
    if (left < size && list[left] > list[largest]) {
        largest = left;
    }
    if (right < size && list[right] > list[largest]) {
        largest = right;
    }
    if (largest !== index) {
        [list[index], list[largest]] = [list[largest], list[index]];
        heapify(list, size, largest);
    }
    return list;
}

function heapsort(list) {
    const size = list.length;
    let index = ~~(size / 2 - 1);
    let last = size - 1;
    while (index >= 0) {
        heapify(list, size, --index);
    }
    while (last >= 0) {
        [list[0], list[last]] = [list[last], list[0]];
        heapify(list, --last, 0);
    }
    return list;
}

heapsort([4, 7, 2, 6, 4, 1, 8, 3]);