Swift: 297.Serialize and Deserialize BT

Author: aifedorov

swift/0297-serialize-and-deserialize-binary-tree.swift

@@ -0,0 +1,48 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public var val: Int
+ *     public var left: TreeNode?
+ *     public var right: TreeNode?
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.left = nil
+ *         self.right = nil
+ *     }
+ * }
+ */
+
+class Codec {
+
+    func preorderTraversal(_ root: TreeNode?) -> String {
+        guard let root = root else { return "x" }
+        return "\(root.val)" + " " + preorderTraversal(root.left) + " " + preorderTraversal(root.right)
+    }
+
+    func serialize(_ root: TreeNode?) -> String {
+        return preorderTraversal(root)
+    }
+    
+    func preorderTraversal(_ data: [String], _ index: inout Int) -> TreeNode? {
+        guard index < data.count else { return nil }
+        guard data[index] != "x" else { return nil }
+        guard let val = Int(data[index]) else { return nil }
+        let current = TreeNode(val)
+        index += 1
+        current.left = preorderTraversal(data, &index)
+        index += 1
+        current.right = preorderTraversal(data, &index)
+        return current
+    }
+    
+    func deserialize(_ data: String) -> TreeNode? {
+        guard !data.isEmpty else { return nil }
+        var index = 0
+        return preorderTraversal(data.split(separator: " ").map { String($0) }, &index)
+    }
+}
+
+// Your Codec object will be instantiated and called as such:
+// var ser = Codec()
+// var deser = Codec()
+// deser.deserialize(ser.serialize(root))