WuchiOnline

public class MaxHeap<T> where T: System.IComparable<T> 
{
    public List<T> heapList {get; set;}

    public int Count {get => heapList.Count;}

    private int GetLeftChildIndex(int elementIndex) => 2 * elementIndex + 1;
    private int GetRightChildIndex(int elementIndex) => 2 * elementIndex + 2;
    private int GetParentIndex(int elementIndex) => (elementIndex - 1) / 2;

WuchiOnline

public class MinHeap<T> where T: System.IComparable<T> 
{
    public List<T> heapList {get; set;}

    public int Count {get => heapList.Count;}

    private int GetLeftChildIndex(int elementIndex) => 2 * elementIndex + 1;
    private int GetRightChildIndex(int elementIndex) => 2 * elementIndex + 2;
    private int GetParentIndex(int elementIndex) => (elementIndex - 1) / 2;