Update 0096.不同的二叉搜索树，添加C#

problems/0096.不同的二叉搜索树.md

@@ -328,6 +328,25 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int NumTrees(int n)
+    {
+        int[] dp = new int[n + 1];
+        dp[0] = 1;
+        for (int i = 1; i <= n; i++)
+        {
+            for (int j = 1; j <= i; j++)
+            {
+                dp[i] += dp[j - 1] * dp[i - j];
+            }
+        }
+        return dp[n];
+    }
+}
+```
 
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