public void ConstructTree()
{
DLLNode node1 = new DLLNode()
{
Value = 1
};
DLLNode node2 = new DLLNode()
{
Value = 2
};
DLLNode node3 = new DLLNode()
{
Value = 3
};
DLLNode node4 = new DLLNode()
{
Value = 4
};
DLLNode node5 = new DLLNode()
{
Value = 5
};
DLLNode node6 = new DLLNode()
{
Value = 6
};
DLLNode node7 = new DLLNode()
{
Value = 7
};
node7.Parent = node6.Parent = node3;
node3.Left = node6;
node3.Right = node7;
node5.Parent = node4.Parent = node2;
node2.Left = node4;
node2.Right = node5;
node2.Parent = node3.Parent = node1;
node1.Left = node2;
node1.Right = node3;
node1.Parent = null;
Console.WriteLine(FindAncestor(node4, node5).Value.ToString());
Console.Read();
}
public DLLNode FindAncestor(DLLNode first, DLLNode second)
{
if (first == null || second == null)
{
return(null);
}
DLLNode firstPtr = first;
DLLNode secondPtr = second;
DLLNode Ancestor = null;
while (firstPtr.Parent != null && secondPtr.Parent != null)
{
if (firstPtr.Parent == secondPtr.Parent)
{
Ancestor = firstPtr.Parent;
break;
}
firstPtr = firstPtr.Parent;
secondPtr = secondPtr.Parent;
}
if (Ancestor == null && firstPtr.Parent != null && secondPtr.Parent == null)
{
while (firstPtr.Parent != null)
{
firstPtr = firstPtr.Parent;
if (firstPtr == secondPtr)
{
Ancestor = firstPtr;
}
}
}
else if (Ancestor == null && firstPtr.Parent == null && secondPtr.Parent != null)
{
while (secondPtr.Parent != null)
{
secondPtr = secondPtr.Parent;
if (firstPtr == secondPtr)
{
Ancestor = firstPtr;
}
}
}
return(Ancestor);
}