feat: add swift implementation to lcof problem: No.48 (#2933)

lcof/面试题48. 最长不含重复字符的子字符串/README.md

@@ -220,6 +220,30 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var ans = 0
+        var j = 0
+        var vis = Set<Character>()
+        let sArray = Array(s)
+
+        for i in 0..<sArray.count {
+            while vis.contains(sArray[i]) {
+                vis.remove(sArray[j])
+                j += 1
+            }
+            vis.insert(sArray[i])
+            ans = max(ans, i - j + 1)
+        }
+
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题48. 最长不含重复字符的子字符串/Solution.swift

@@ -0,0 +1,19 @@
+class Solution {
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var ans = 0
+        var j = 0
+        var vis = Set<Character>()
+        let sArray = Array(s)
+        
+        for i in 0..<sArray.count {
+            while vis.contains(sArray[i]) {
+                vis.remove(sArray[j])
+                j += 1
+            }
+            vis.insert(sArray[i])
+            ans = max(ans, i - j + 1)
+        }
+        
+        return ans
+    }
+}