添加0541. 反转字符串II Swift版本

problems/0541.反转字符串II.md

@@ -226,6 +226,28 @@ var reverseStr = function(s, k) {
 
 ```
 
+Swift:
+
+```swift
+func reverseStr(_ s: String, _ k: Int) -> String {
+    var ch = Array(s)
+
+    for i in stride(from: 0, to: ch.count, by: 2 * k) {
+        var left = i
+        var right = min(s.count - 1, left + k - 1)
+      
+        while left < right {
+            (ch[left], ch[right]) = (ch[right], ch[left])
+            left += 1
+            right -= 1
+        }
+    }
+    return String(ch)
+}
+```
+
+
+
 
 
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