Day i do not know

700. Search in a Binary Search Tree/Solution.cs

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+namespace _700._Search_in_a_Binary_Search_Tree;
+
+public class Solution
+{
+    public TreeNode? SearchBST(TreeNode? root, int val)
+    {
+        Stack<TreeNode> stack = new Stack<TreeNode>();
+        if (root != null)
+            stack.Push(root);
+        while (stack.Count > 0)
+        {
+            TreeNode cur = stack.Pop();
+            if (cur.right != null)
+                stack.Push(cur.right);
+            if (cur.left != null)
+                stack.Push(cur.left);
+            if(cur.val == val)
+                return cur;
+        }
+        return null;
+    }
+}