feat: Add solution for LeetCode problem 206

Author: WhiteHyun

reverse-linked-list/WhiteHyun.swift

@@ -0,0 +1,20 @@
+//
+//  206. Reverse Linked List.swift
+//  https://leetcode.com/problems/reverse-linked-list/description/
+//  Algorithm
+//
+//  Created by 홍승현 on 2024/05/04.
+//
+
+import Foundation
+
+final class LeetCode206 {
+  func reverseList(_ node: ListNode?, _ prev: ListNode? = nil) -> ListNode? {
+    guard let node else { return prev }
+
+    let next = node.next
+    node.next = prev
+
+    return reverseList(next, node)
+  }
+}