feat: add swift implementation to lcof problem: No.22 (doocs#2881)

Author: klever34

lcof/面试题22. 链表中倒数第k个节点/README.md

@@ -226,6 +226,40 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+/* public class ListNode {
+*     var val: Int
+*     var next: ListNode?
+*     init(_ val: Int) {
+*         self.val = val
+*         self.next = nil
+*     }
+* }
+*/
+
+class Solution {
+    func getKthFromEnd(_ head: ListNode?, _ k: Int) -> ListNode? {
+        var slow = head
+        var fast = head
+        var k = k
+
+        while k > 0 {
+            fast = fast?.next
+            k -= 1
+        }
+
+        while fast != nil {
+            slow = slow?.next
+            fast = fast?.next
+        }
+
+        return slow
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题22. 链表中倒数第k个节点/Solution.swift

@@ -0,0 +1,29 @@
+/* public class ListNode {
+*     var val: Int
+*     var next: ListNode?
+*     init(_ val: Int) {
+*         self.val = val
+*         self.next = nil
+*     }
+* }
+*/
+
+class Solution {
+    func getKthFromEnd(_ head: ListNode?, _ k: Int) -> ListNode? {
+        var slow = head
+        var fast = head
+        var k = k
+        
+        while k > 0 {
+            fast = fast?.next
+            k -= 1
+        }
+        
+        while fast != nil {
+            slow = slow?.next
+            fast = fast?.next
+        }
+        
+        return slow
+    }
+}