Update0376.摆动序列，添加C#

problems/0376.摆动序列.md

@@ -692,6 +692,27 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int WiggleMaxLength(int[] nums)
+    {
+        if (nums.Length < 2) return nums.Length;
+        int curDiff = 0, preDiff = 0, res = 1;
+        for (int i = 0; i < nums.Length - 1; i++)
+        {
+            curDiff = nums[i + 1] - nums[i];
+            if ((curDiff > 0 && preDiff <= 0) || (curDiff < 0 && preDiff >= 0))
+            {
+                res++;
+                preDiff = curDiff;
+            }
+        }
+        return res;
+    }
+}
+```
 
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