feat: add swift implementation to lcof problem: No.18 (doocs#2877)

Author: klever34

Diff for: lcof/面试题18. 删除链表的节点/README.md

@@ -237,6 +237,39 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     var val: Int
+ *     var next: ListNode?
+ *     init(_ val: Int, _ next: ListNode? = nil) {
+ *         self.val = val
+ *         self.next = next
+ *     }
+ * }
+ */
+
+class Solution {
+    func deleteNode(_ head: ListNode?, _ val: Int) -> ListNode? {
+        let dummy = ListNode(0, head)
+        var current: ListNode? = dummy
+        
+        while current?.next != nil {
+            if current?.next?.val == val {
+                current?.next = current?.next?.next
+                break
+            }
+            current = current?.next
+        }
+        
+        return dummy.next
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

Diff for: lcof/面试题18. 删除链表的节点/Solution.swift

@@ -0,0 +1,28 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     var val: Int
+ *     var next: ListNode?
+ *     init(_ val: Int, _ next: ListNode? = nil) {
+ *         self.val = val
+ *         self.next = next
+ *     }
+ * }
+ */
+
+class Solution {
+    func deleteNode(_ head: ListNode?, _ val: Int) -> ListNode? {
+        let dummy = ListNode(0, head)
+        var current: ListNode? = dummy
+        
+        while current?.next != nil {
+            if current?.next?.val == val {
+                current?.next = current?.next?.next
+                break
+            }
+            current = current?.next
+        }
+        
+        return dummy.next
+    }
+}