feat: add swift implementation to lcof2 problem: No.048

lcof2/剑指 Offer II 048. 序列化与反序列化二叉树/README.md

@@ -314,6 +314,78 @@ const rdeserialize = dataList => {
  */
 ```
 
+#### Swift
+
+```swift
+/* class TreeNode {
+*     var val: Int
+*     var left: TreeNode?
+*     var right: TreeNode?
+*     init() {
+*         self.val = 0
+*         self.left = nil
+*         self.right = nil
+*     }
+*     init(_ val: Int) {
+*         self.val = val
+*         self.left = nil
+*         self.right = nil
+*     }
+*     init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+*         self.val = val
+*         self.left = left
+*         self.right = right
+*     }
+* }
+*/
+
+class Codec {
+    private let NULL = "#"
+    private let SEP = ","
+
+    func serialize(_ root: TreeNode?) -> String {
+        guard let root = root else { return "" }
+        var sb = ""
+        preorder(root, &sb)
+        return sb
+    }
+
+    private func preorder(_ root: TreeNode?, _ sb: inout String) {
+        guard let root = root else {
+            sb += NULL + SEP
+            return
+        }
+        sb += "\(root.val)" + SEP
+        preorder(root.left, &sb)
+        preorder(root.right, &sb)
+    }
+
+    func deserialize(_ data: String) -> TreeNode? {
+        guard !data.isEmpty else { return nil }
+        var vals = data.split(separator: Character(SEP)).map { String($0) }
+        return deserialize(&vals)
+    }
+
+    private func deserialize(_ vals: inout [String]) -> TreeNode? {
+        if vals.isEmpty { return nil }
+        let first = vals.removeFirst()
+        if first == NULL {
+            return nil
+        }
+        let root = TreeNode(Int(first)!)
+        root.left = deserialize(&vals)
+        root.right = deserialize(&vals)
+        return root
+    }
+}
+/**
+ * Your functions will be called as such:
+ * let codec = Codec()
+ * let serializedDatacodec.serialize(root);
+ * codec.deserialize(serializedData);
+ */
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 048. 序列化与反序列化二叉树/Solution.swift

@@ -0,0 +1,67 @@
+/* class TreeNode {
+*     var val: Int
+*     var left: TreeNode?
+*     var right: TreeNode?
+*     init() {
+*         self.val = 0
+*         self.left = nil
+*         self.right = nil
+*     }
+*     init(_ val: Int) {
+*         self.val = val
+*         self.left = nil
+*         self.right = nil
+*     }
+*     init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+*         self.val = val
+*         self.left = left
+*         self.right = right
+*     }
+* }
+*/
+
+class Codec {
+    private let NULL = "#"
+    private let SEP = ","
+
+    func serialize(_ root: TreeNode?) -> String {
+        guard let root = root else { return "" }
+        var sb = ""
+        preorder(root, &sb)
+        return sb
+    }
+
+    private func preorder(_ root: TreeNode?, _ sb: inout String) {
+        guard let root = root else {
+            sb += NULL + SEP
+            return
+        }
+        sb += "\(root.val)" + SEP
+        preorder(root.left, &sb)
+        preorder(root.right, &sb)
+    }
+
+    func deserialize(_ data: String) -> TreeNode? {
+        guard !data.isEmpty else { return nil }
+        var vals = data.split(separator: Character(SEP)).map { String($0) }
+        return deserialize(&vals)
+    }
+
+    private func deserialize(_ vals: inout [String]) -> TreeNode? {
+        if vals.isEmpty { return nil }
+        let first = vals.removeFirst()
+        if first == NULL {
+            return nil
+        }
+        let root = TreeNode(Int(first)!)
+        root.left = deserialize(&vals)
+        root.right = deserialize(&vals)
+        return root
+    }
+}
+/**
+ * Your functions will be called as such:
+ * let codec = Codec()
+ * let serializedDatacodec.serialize(root);
+ * codec.deserialize(serializedData);
+ */