From 34de1fd8b0fde25caef3626bf6a848f080607aed Mon Sep 17 00:00:00 2001
From: eeee0717 <70054568+eeee0717@users.noreply.github.com>
Date: Tue, 21 Nov 2023 09:07:56 +0800
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---
 problems/0404.左叶子之和.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md
index c1ad602d..6dfcc886 100644
--- a/problems/0404.左叶子之和.md
+++ b/problems/0404.左叶子之和.md
@@ -651,6 +651,23 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+// 递归
+public int SumOfLeftLeaves(TreeNode root)
+{
+    if (root == null) return 0;
+
+    int leftValue = SumOfLeftLeaves(root.left);
+    if (root.left != null && root.left.left == null && root.left.right == null)
+    {
+        leftValue += root.left.val;
+    }
+    int rightValue = SumOfLeftLeaves(root.right);
+    return leftValue + rightValue;
+
+}
+```
 
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