feat: add swift implementation to lcof2 problem: No.016 (doocs#3004)

Author: klever34

lcof2/剑指 Offer II 016. 不含重复字符的最长子字符串/README.md

@@ -197,6 +197,29 @@ function lengthOfLongestSubstring(s: string): number {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var ss = Array(repeating: false, count: 128)
+        var ans = 0
+        var j = s.startIndex
+
+        for i in s.indices {
+            let c = s[i]
+            while ss[Int(c.asciiValue!)] {
+                ss[Int(s[j].asciiValue!)] = false
+                j = s.index(after: j)
+            }
+            ans = max(ans, s.distance(from: j, to: i) + 1)
+            ss[Int(c.asciiValue!)] = true
+        }
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 016. 不含重复字符的最长子字符串/Solution.swift

@@ -0,0 +1,18 @@
+class Solution {
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var ss = Array(repeating: false, count: 128)
+        var ans = 0
+        var j = s.startIndex
+        
+        for i in s.indices {
+            let c = s[i]
+            while ss[Int(c.asciiValue!)] {
+                ss[Int(s[j].asciiValue!)] = false
+                j = s.index(after: j)
+            }
+            ans = max(ans, s.distance(from: j, to: i) + 1)
+            ss[Int(c.asciiValue!)] = true
+        }
+        return ans
+    }
+}