DecimalSearchContains.swift

class DecimalSearchTree {
    ...
    func contains(numbers: String) -> Bool{
            // Return true if this Decimal search tree contains a path at contains
            // all the numbers iteratively.

            var currentNode: DecimalTreeNode? = self.root

            for character in numbers {
                let index = Int(String(character))

                if let newNode = currentNode?.next[index!] {
                    currentNode = newNode
                } else {
                    currentNode = nil
                    break
                }
            }
            return currentNode != nil
        }
}