diff --git a/Encode and Decode Tree/EncodeAndDecodeTree.playground/Contents.swift b/Encode and Decode Tree/EncodeAndDecodeTree.playground/Contents.swift
index dbd2fd180..44c2440d5 100644
--- a/Encode and Decode Tree/EncodeAndDecodeTree.playground/Contents.swift	
+++ b/Encode and Decode Tree/EncodeAndDecodeTree.playground/Contents.swift	
@@ -1,13 +1,10 @@
 //: Playground - noun: a place where people can play
 
-
-func printTree(_ root: TreeNode?) {
+func printTree(_ root: BinaryNode<String>?) {
     guard let root = root else {
         return
     }
 
-    var pointer = root
-
     let leftVal = root.left == nil ? "nil" : root.left!.val
     let rightVal = root.right == nil ? "nil" : root.right!.val
 
@@ -17,25 +14,25 @@ func printTree(_ root: TreeNode?) {
     printTree(root.right)
 }
 
-let s = EncodeAndDecodeTree()
+let coder = BinaryNodeCoder<String>()
 
-let node1 = TreeNode("a")
-let node2 = TreeNode("b")
-let node3 = TreeNode("c")
-let node4 = TreeNode("d")
-let node5 = TreeNode("e")
+let node1 = BinaryNode("a")
+let node2 = BinaryNode("b")
+let node3 = BinaryNode("c")
+let node4 = BinaryNode("d")
+let node5 = BinaryNode("e")
 
 node1.left = node2
 node1.right = node3
 node3.left = node4
 node3.right = node5
 
-let encodeStr = s.encode(node1)
+let encodeStr = try coder.encode(node1)
 print(encodeStr)
 // "a b # # c d # # e # #"
 
 
-let root = s.decode(encodeStr)
+let root: BinaryNode<String> = coder.decode(from: encodeStr)!
 print("Tree:")
 printTree(root)
 /*
diff --git a/Encode and Decode Tree/EncodeAndDecodeTree.playground/Sources/EncodeAndDecodeTree.swift b/Encode and Decode Tree/EncodeAndDecodeTree.playground/Sources/EncodeAndDecodeTree.swift
index e9d22f8a9..10bb277f5 100644
--- a/Encode and Decode Tree/EncodeAndDecodeTree.playground/Sources/EncodeAndDecodeTree.swift	
+++ b/Encode and Decode Tree/EncodeAndDecodeTree.playground/Sources/EncodeAndDecodeTree.swift	
@@ -8,97 +8,88 @@
 
 import Foundation
 
-public class TreeNode {
-    public var val: String
-    public var left: TreeNode?
-    public var right: TreeNode?
-
-    public init(_ val: String, left: TreeNode? = nil, right: TreeNode? = nil) {
-        self.val = val
-        self.left = left
-        self.right = right
-    }
+protocol BinaryNodeEncoder {
+  func encode<T>(_ node: BinaryNode<T>?) throws -> String
 }
 
-public class EncodeAndDecodeTree {
-    private var encodeStr = ""
-    private var ret: [String] = []
+protocol BinaryNodeDecoder {
+  func decode<T>(from string: String) -> BinaryNode<T>?
+}
 
-    public init() {}
+public class BinaryNodeCoder<T: Comparable>: BinaryNodeEncoder, BinaryNodeDecoder {
 
-    public func encode(_ root: TreeNode?) -> String {
-        encodeIt(root)
+  // MARK: Private
 
-        return encodeStr
-    }
+  private let separator: Character = ","
+  private let nilNode = "X"
 
-    public func decode(_ data: String) -> TreeNode? {
-        var s = data
-        while (s.contains(" ")) {
-            let index = s.index(of: " ")
-            let endIndex = s.index(before: index)
-            let element = s[s.startIndex...endIndex]
-            ret.append(element)
-            let range = ClosedRange(uncheckedBounds: (lower: s.startIndex, upper: index))
-            s.removeSubrange(range)
-        }
-
-        if ret.count == 0 {
-            return nil
-        }
-
-        var dep = 0
-        let root = decodeIt(&dep)
-
-        return root
+  private func decode<T>(from array: inout [String]) -> BinaryNode<T>? {
+    guard !array.isEmpty else {
+      return nil
     }
 
-    private func getNode(_ element: String) -> TreeNode? {
-        if element == "#" {
-            return nil
-        }
+    let value = array.removeLast()
 
-        return TreeNode(element)
+    guard value != nilNode, let val = value as? T else {
+      return nil
     }
 
-    private func decodeIt(_ dep: inout Int) -> TreeNode? {
-        guard let currentNode = getNode(ret[dep]) else {
-            return nil
-        }
+    let node = BinaryNode<T>(val)
+    node.left = decode(from: &array)
+    node.right = decode(from: &array)
 
-        dep += 1
-        let left = decodeIt(&dep)
-        dep += 1
-        let right = decodeIt(&dep)
+    return node
+  }
 
-        currentNode.left = left
-        currentNode.right = right
+  // MARK: Public
 
-        return currentNode
+  public init() {}
+
+  public func encode<T>(_ node: BinaryNode<T>?) throws -> String {
+    var str = ""
+    node?.preOrderTraversal { data in
+      if let data = data {
+        let string = String(describing: data)
+        str.append(string)
+      } else {
+        str.append(nilNode)
+      }
+      str.append(separator)
     }
 
-    private func encodeIt(_ root: TreeNode?) {
-        guard let root = root else {
-            encodeStr += "# "
-            return
-        }
+    return str
+  }
 
-        encodeStr += root.val + " "
-        encodeIt(root.left)
-        encodeIt(root.right)
-    }
+  public func decode<T>(from string: String) -> BinaryNode<T>? {
+    var components = string.split(separator: separator).reversed().map(String.init)
+    return decode(from: &components)
+  }
 }
 
-extension String {
-    func index(of target: Character) -> String.Index {
-        var i = 0
-        for c in self.characters {
-            if c == target {
-                return self.index(self.startIndex, offsetBy: i)
-            }
-            i += 1
-        }
-
-        return self.endIndex
+public class BinaryNode<Element: Comparable> {
+  public var val: Element
+  public var left: BinaryNode?
+  public var right: BinaryNode?
+
+  public init(_ val: Element, left: BinaryNode? = nil, right: BinaryNode? = nil) {
+    self.val = val
+    self.left = left
+    self.right = right
+  }
+
+  public func preOrderTraversal(visit: (Element?) throws -> ()) rethrows {
+    try visit(val)
+
+    if let left = left {
+      try left.preOrderTraversal(visit: visit)
+    } else {
+      try visit(nil)
+    }
+
+    if let right = right {
+      try right.preOrderTraversal(visit: visit)
+    } else {
+      try visit(nil)
     }
+  }
 }
diff --git a/Encode and Decode Tree/EncodeAndDecodeTree.swift b/Encode and Decode Tree/EncodeAndDecodeTree.swift
index daa3c3ea2..6ec8a3046 100644
--- a/Encode and Decode Tree/EncodeAndDecodeTree.swift	
+++ b/Encode and Decode Tree/EncodeAndDecodeTree.swift	
@@ -8,97 +8,88 @@
 
 import Foundation
 
-public class TreeNode {
-    public var val: String
-    public var left: TreeNode?
-    public var right: TreeNode?
-
-    public init(_ val: String, left: TreeNode? = nil, right: TreeNode? = nil) {
-        self.val = val
-        self.left = left
-        self.right = right
-    }
+protocol BinaryNodeEncoder {
+  func encode<T>(_ node: BinaryNode<T>?) throws -> String
 }
 
-public class EncodeAndDecodeTree {
-    private var encodeStr = ""
-    private var ret: [String] = []
+protocol BinaryNodeDecoder {
+  func decode<T>(from string: String) -> BinaryNode<T>?
+}
 
-    public init() {}
+public class BinaryNodeCoder<T: Comparable>: BinaryNodeEncoder, BinaryNodeDecoder {
 
-    public func encode(_ root: TreeNode?) -> String {
-        encodeIt(root)
+  // MARK: Private
 
-        return encodeStr
-    }
+  private let separator: Character = ","
+  private let nilNode = "X"
 
-    public func decode(_ data: String) -> TreeNode? {
-        var s = data
-        while (s.contains(" ")) {
-            let index = s.index(of: " ")
-            let endIndex = s.index(before: index)
-            let element = s[s.startIndex...endIndex]
-            ret.append(element)
-            let range = ClosedRange(uncheckedBounds: (lower: s.startIndex, upper: index))
-            s.removeSubrange(range)
-        }
-
-        if ret.count == 0 {
-            return nil
-        }
-
-        var dep = 0
-        let root = decodeIt(&dep)
-
-        return root
+  private func decode<T>(from array: inout [String]) -> BinaryNode<T>? {
+    guard !array.isEmpty else {
+      return nil
     }
 
-    private func getNode(_ element: String) -> TreeNode? {
-        if element == "#" {
-            return nil
-        }
+    let value = array.removeLast()
 
-        return TreeNode(element)
+    guard value != nilNode, let val = value as? T else {
+      return nil
     }
 
-    private func decodeIt(_ dep: inout Int) -> TreeNode? {
-        guard let currentNode = getNode(ret[dep]) else {
-            return nil
-        }
+    let node = BinaryNode<T>(val)
+    node.left = decode(from: &array)
+    node.right = decode(from: &array)
 
-        dep += 1
-        let left = decodeIt(&dep)
-        dep += 1
-        let right = decodeIt(&dep)
+    return node
+  }
 
-        currentNode.left = left
-        currentNode.right = right
+  // MARK: Public
 
-        return currentNode
+  public init() {}
+
+  public func encode<T>(_ node: BinaryNode<T>?) throws -> String {
+    var str = ""
+    node?.preOrderTraversal { data in
+      if let data = data {
+        let string = String(describing: data)
+        str.append(string)
+      } else {
+        str.append(nilNode)
+      }
+      str.append(separator)
     }
 
-    private func encodeIt(_ root: TreeNode?) {
-        guard let root = root else {
-            encodeStr += "# "
-            return
-        }
+    return str
+  }
 
-        encodeStr += root.val + " "
-        encodeIt(root.left)
-        encodeIt(root.right)
-    }
+  public func decode<T>(from string: String) -> BinaryNode<T>? {
+    var components = string.split(separator: separator).reversed().map(String.init)
+    return decode(from: &components)
+  }
 }
 
-extension String {
-    func index(of target: Character) -> String.Index {
-        var i = 0
-        for c in self.characters {
-            if c == target {
-                return self.index(self.startIndex, offsetBy: i)
-            }
-            i += 1
-        }
-        
-        return self.endIndex
+public class BinaryNode<Element: Comparable> {
+  public var val: Element
+  public var left: BinaryNode?
+  public var right: BinaryNode?
+
+  public init(_ val: Element, left: BinaryNode? = nil, right: BinaryNode? = nil) {
+    self.val = val
+    self.left = left
+    self.right = right
+  }
+
+  public func preOrderTraversal(visit: (Element?) throws -> ()) rethrows {
+    try visit(val)
+
+    if let left = left {
+      try left.preOrderTraversal(visit: visit)
+    } else {
+      try visit(nil)
+    }
+
+    if let right = right {
+      try right.preOrderTraversal(visit: visit)
+    } else {
+      try visit(nil)
     }
+  }
 }