TheAlgorithms-C-Plus-Plus/sorting/heap_sort.cpp

#include <iostream>

void max_heapify(int *a, int i, int n) {
    int j, temp;
    temp = a[i];
    j = 2 * i;
    while (j <= n) {
        if (j < n && a[j + 1] > a[j])
            j = j + 1;
        if (temp > a[j]) {
            break;
        } else if (temp <= a[j]) {
            a[j / 2] = a[j];
            j = 2 * j;
        }
    }
    a[j / 2] = temp;
    return;
}

void heapsort(int *a, int n) {
    int i, temp;
    for (i = n; i >= 2; i--) {
        temp = a[i];
        a[i] = a[1];
        a[1] = temp;
        max_heapify(a, 1, i - 1);
    }
}

void build_maxheap(int *a, int n) {
    int i;
    for (i = n / 2; i >= 1; i--) {
        max_heapify(a, i, n);
    }
}

int main() {
    int n, i;
    std::cout << "Enter number of elements of array\n";
    std::cin >> n;
    int a[20];
    for (i = 1; i <= n; i++) {
        std::cout << "Enter Element " << (i) << std::endl;
        std::cin >> a[i];
    }
    build_maxheap(a, n);
    heapsort(a, n);
    std::cout << "Sorted Output\n";
    for (i = 1; i <= n; i++) {
        std::cout << a[i] << std::endl;
    }
    std::getchar();
}