From a355627ee1fc4d6bb46e3ea2a9ebac35ae337a77 Mon Sep 17 00:00:00 2001
From: Jihyun Son <sonjh1217@naver.com>
Date: Wed, 3 Sep 2025 08:58:50 +0900
Subject: [PATCH 1/2] solve

---
 reverse-linked-list/sonjh1217.swift | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 reverse-linked-list/sonjh1217.swift

diff --git a/reverse-linked-list/sonjh1217.swift b/reverse-linked-list/sonjh1217.swift
new file mode 100644
index 000000000..36fd1a0b1
--- /dev/null
+++ b/reverse-linked-list/sonjh1217.swift
@@ -0,0 +1,26 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public var val: Int
+ *     public var next: ListNode?
+ *     public init() { self.val = 0; self.next = nil; }
+ *     public init(_ val: Int) { self.val = val; self.next = nil; }
+ *     public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
+ * }
+ */
+class Solution {
+    // O(n) time / O(1) space
+    func reverseList(_ head: ListNode?) -> ListNode? {
+        var node = head
+        var lastNode: ListNode? = nil
+        
+        while node != nil {
+            let next = node?.next
+            node?.next = lastNode
+            lastNode = node
+            node = next
+        }
+        
+        return lastNode
+    }
+}

From f97fc0a2280902e9bab56ab37855fe7f6db38526 Mon Sep 17 00:00:00 2001
From: Jihyun Son <sonjh1217@naver.com>
Date: Wed, 3 Sep 2025 10:03:53 +0900
Subject: [PATCH 2/2] solve

---
 .../sonjh1217.swift                           | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 longest-substring-without-repeating-characters/sonjh1217.swift

diff --git a/longest-substring-without-repeating-characters/sonjh1217.swift b/longest-substring-without-repeating-characters/sonjh1217.swift
new file mode 100644
index 000000000..a3072a91a
--- /dev/null
+++ b/longest-substring-without-repeating-characters/sonjh1217.swift
@@ -0,0 +1,19 @@
+class Solution {
+    // O(n) time / O(n) space
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var lastIndexByCharacter = [Character: Int]()
+        var start = 0
+        var maxLenth = 0
+
+        for (i, character) in s.enumerated() {
+            if let lastIndex = lastIndexByCharacter[character],
+                lastIndex >= start {
+                start = lastIndex + 1
+            }
+            lastIndexByCharacter[character] = i
+            maxLenth = max(maxLenth, i - start + 1)
+        }
+        return maxLenth
+    }
+}
+