basicDecimalTree.swift

class DecimalSearchTree{
    
    let root: DecimalTreeNode = DecimalTreeNode(data: "+")
    var size: Int = 11  // number of nodes in the tree and the unuse node
    var usedSize: Int = 0 // Number of nodes that are used
    
    func isEmpty() -> Bool{
        // Return true if this decimal search tree is empty (has no nodes)
        return self.root.isLeaf()
    }
    
    func height() -> Int{
        // Return the height of this tree (the number of edges on the longest
        // downward path from this tree's root node to a descendant leaf node).
        return self.root.height()
    }
}