feat: add swift implementation to lcof2 problem: No.023 (#3011)

Author: klever34

lcof2/剑指 Offer II 023. 两个链表的第一个重合节点/Solution.swift

@@ -0,0 +1,23 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public var val: Int
+ *     public var next: ListNode?
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.next = nil
+ *     }
+ * }
+ */
+
+class Solution {
+    func getIntersectionNode(_ headA: ListNode?, _ headB: ListNode?) -> ListNode? {
+        var a = headA
+        var b = headB
+        while a !== b {
+            a = a == nil ? headB : a?.next
+            b = b == nil ? headA : b?.next
+        }
+        return a
+    }
+}