height.swift

class DecimalTreeNode {
    ...
    func height() -> Int{
        /*Return the height of the node (the number of edges on the longest
         downward path from this node to a descendant leaf node).*/
        // Early break
        if self.isLeaf(){
            return 0
        }
        // Create a array of int to keep track of the height of each branch
        var tenPath = Array<Int>(repeating: 0, count: 10)
        
        // Traverse each child node
        for path in 0 ... 10 {
            // Check if there is a node to begin with
            if let newPath = self.next[path]{
                tenPath[path] += newPath.height()
            }
        }
        // The program have travese all of it children
        return tenPath.max()! + 1
    }
}