添加 0344.反转字符串 C#版本

problems/0344.反转字符串.md

@@ -232,6 +232,19 @@ void reverseString(char* s, int sSize){
 }
 ```
 
+C#：
+```csharp
+public class Solution
+{
+    public void ReverseString(char[] s)
+    {
+        for (int i = 0, j = s.Length - 1; i < j; i++, j--)
+        {
+            (s[i], s[j]) = (s[j], s[i]);
+        }
+    }
+}
+```
 
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