HW2_heap_sort

#include <cstdio>
#include <cstdlib>
#include <ctime>
#define _CRT_SECURE_NO_WARNINGS

int * generate(int n)
{
    int * arr = (int *)calloc(n, sizeof(int));
    for (int i = 0; i < n; ++i)
    {
        arr[i] = rand();
    }
    return arr;
}

void swap(int &a, int &b)
{
    int t = a;
    a = b;
    b = t;
}

void siftup(int * heap, int i)
{
    while (heap[i] > heap[(i - 1) / 2])
    {
        swap(heap[i], heap[(i - 1) / 2]);
        i = (i - 1) / 2;
    }
}

void siftdown(int * heap, int i, int n)
{
    int left = 0, right = 0, j = 0;
    while (2 * i + 1 < n)
    {
        left = 2 * i + 1;
        right = 2 * i + 2;
        j = left;
        if (right < n && heap[right] > heap[left])
            j = right;
        if (heap[i] > heap[j])
            return;
        swap(heap[i], heap[j]);
        i = j;
    }
}

void add(int * heap, int i, int &n)
{
    n++;
    heap[n - 1] = i;
    siftup(heap, n - 1);
}

int delete_max(int *heap, int &n)
{
    int min = heap[0];
    heap[0] = heap[n - 1];
    n--;
    siftdown(heap, 0, n);
    return min;
}

int main()
{
    int n = 0, h = 0, t = 0;
    srand(time(NULL));
    scanf("%d", &n);
    int * arr = generate(n);
    for (int i = 0; i < n; ++i)
    {
        add(arr, arr[i], h);
    }
    for (int i = n - 1; i > 0; --i)
        arr[i] = delete_max(arr, h);
    for (int i = 1; i < n; ++i)
    {
        if (arr[i - 1] > arr[i])
        {
            printf("ERROR");
            t++;
            break;
        }
    }
    if (!t)
    {
        printf("OK");
    }
    free(arr);
    return 0;
}