/// <summary>
/// returns the largest BST in a BT
/// </summary>
/// <param name="root"></param>
/// <returns></returns>
private static MinMaX LargestBSTree(Tree root)
{
if (root == null)
{
return(new MinMaX());
}
MinMaX leftMinMax = LargestBSTree(root.Left);
MinMaX rightMinMax = LargestBSTree(root.Right);
MinMaX current = new MinMaX();
if (leftMinMax.IsBST == false || rightMinMax.IsBST == false || (leftMinMax.Max > root.Data) || (rightMinMax.Min < root.Data))
{
current.IsBST = false;
current.Size = Math.Max(leftMinMax.Size, rightMinMax.Size);
return(current);
}
current.IsBST = true;
current.Size = leftMinMax.Size + rightMinMax.Size + 1;
current.Min = root.Left != null ? leftMinMax.Min : root.Data;
current.Max = root.Right != null ? rightMinMax.Max : root.Data;
return(current);
}
public static int LargestBST(Tree root)
{
MinMaX m = LargestBSTree(root);
return(m.Size);
}