Day i do not know

101. Symmetric Tree/Solution.cs

@@ -0,0 +1,20 @@
+namespace _101._Symmetric_Tree;
+
+public class Solution
+{
+    public bool IsSymmetric(TreeNode root)
+    {
+        return Recursion(root.left, root.right);
+    }
+
+    private bool Recursion(TreeNode? left, TreeNode? right)
+    {
+        if ((left == null) != (right == null))
+            return false;
+        if (left == null || right == null)
+            return true;
+        if (left.val != right.val)
+            return false;
+        return Recursion(left.left, right.right) && Recursion(left.right, right.left);
+    }
+}