堆排序

堆排序

 

堆排序：

template<class T>
void _AdjustDown(T* arr, size_t size, size_t index)
{
    size_t child = index * 2 + 1;
    while (child < size)
    {
        if (child + 1 < size && arr[child + 1] > arr[child])
        {
            ++child;
        }
        if (arr[child]>arr[index])
        {
            swap(arr[child], arr[index]);
            index = child;
            child = child * 2 + 1;
        }
        else
        {
            break;
        }
    }
}

template<class T>
T* HeapSort(T* arr, size_t size)
{
    assert(arr);
    for (int i = (size - 2) / 2; i >= 0; --i)
    {
        _AdjustDown(arr, size, i);
    }
    while (size > 1)
    {
        swap(arr[0], arr[size - 1]);
        --size;
        _AdjustDown(arr, size, 0);
        return arr;
    }
}