public static int[] HeapSort(int[] tab){

        buildMaxHeap(tab);

        return tab;
    }

    private static void buildMaxHeap(int[] tab)
    {


        for(int i=tab.length-1; i >= 0; i--)
        {
            heapify(tab, 0, i);

            int x = tab[i];
            tab[i] = tab[0];
            tab[0] = x;
        }
    }
    private static void heapify(int[] tab, int index, int maxIndex)
    {
        int indexOfLeft = 2 * index + 1;
        int indexOfRight = 2 * index + 2;
        int pomI = index+1;

        if(indexOfRight <= maxIndex) heapify(tab, pomI, maxIndex);

        if(indexOfRight <= maxIndex && tab[index] < tab[indexOfRight])
        {
            int x = tab[indexOfRight];
            tab[indexOfRight] = tab[index];
            tab[index] = x;
        }

        if(indexOfLeft <= maxIndex && tab[index] < tab[indexOfLeft])
        {
            int x = tab[indexOfLeft];
            tab[indexOfLeft] = tab[index];
            tab[index] = x;
        }
    }