feat: add swift implementation to lcci problem: No.02.03 (doocs#2616)

Signed-off-by: Lanre Adedara

Author: klever34

lcci/02.03.Delete Middle Node/README.md

@@ -114,6 +114,26 @@ var deleteNode = function (node) {
 };
 ```
 
+```swift
+/**
+*    public class ListNode {
+*        var val: Int
+*        var next: ListNode?
+*        init(_ x: Int) {
+*            self.val = x
+*            self.next = nil
+*        }
+*    }
+*/
+class Solution {
+    func deleteNode(_ node: ListNode?) {
+        guard let node = node, let next = node.next else { return }
+        node.val = next.val
+        node.next = next.next
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/02.03.Delete Middle Node/README_EN.md

@@ -109,6 +109,26 @@ var deleteNode = function (node) {
 };
 ```
 
+```swift
+/**
+*    public class ListNode {
+*        var val: Int
+*        var next: ListNode?
+*        init(_ x: Int) {
+*            self.val = x
+*            self.next = nil
+*        }
+*    }
+*/
+class Solution {
+    func deleteNode(_ node: ListNode?) {
+        guard let node = node, let next = node.next else { return }
+        node.val = next.val
+        node.next = next.next
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/02.03.Delete Middle Node/Solution.swift

@@ -0,0 +1,17 @@
+/**
+*    public class ListNode {
+*        var val: Int
+*        var next: ListNode?
+*        init(_ x: Int) {
+*            self.val = x
+*            self.next = nil
+*        }
+*    }
+*/
+class Solution {
+    func deleteNode(_ node: ListNode?) {
+        guard let node = node, let next = node.next else { return }
+        node.val = next.val
+        node.next = next.next
+    }
+}