// public Pop
public T Pop()
{
if (_head == null)
{
throw new InvalidOperationException();
}
var tmp = _head.value;
if (_count == 1)
{
_head = null;
_count--;
return(tmp);
}
var parent = GetLastParent(_head, _count - 1);
if (parent.right != null)
{
_head.value = parent.right.value;
parent.right = null;
}
else
{
_head.value = parent.left.value;
parent.left = null;
}
Pop(_head);
_count--;
return(tmp);
}
// public Add
public void Add(T value)
{
if (_head == null)
{
_head = new HeapNode <T>(value);
}
else
{
var current = GetLastParent(_head, _count);
var parent = current;
if (current.left == null)
{
current.left = new HeapNode <T>(value);
current = current.left;
}
else
{
current.right = new HeapNode <T>(value);
current = current.right;
}
current.parent = parent;
Add(current);
}
_count++;
}
// Swap HeapNode values
private static void Swap(HeapNode <T> first, HeapNode <T> second)
{
var tmp = first.value;
first.value = second.value;
second.value = tmp;
}
// Internal Add
private void Add(HeapNode <T> current)
{
if (current == _head || current.CompareTo(current.parent) >= 0)
{
return;
}
Swap(current.parent, current);
Add(current.parent);
}
// Internal Pop
private static void Pop(HeapNode <T> current)
{
if (current.left == null || current.right == null)
{
return;
}
if (current.CompareTo(current.left) <= 0 && current.CompareTo(current.right) <= 0)
{
return;
}
if (current.left.CompareTo(current.right) < 0)
{
Swap(current, current.left);
Pop(current.left);
}
else
{
Swap(current, current.right);
Pop(current.right);
}
}
// using binary string to find the lest parent in tree
private static HeapNode <T> GetLastParent(HeapNode <T> node, int value)
{
var tmp = node;
var binary = Convert.ToString(value + 1, 2);
binary = binary.Substring(1, binary.Length - 2);
var directions = binary.ToCharArray();
foreach (var d in directions)
{
if (d == '0')
{
tmp = tmp.left;
}
else if (d == '1')
{
tmp = tmp.right;
}
}
return(tmp);
}
public int CompareTo(HeapNode <T> node)
{
return(value.CompareTo(node.value));
}