From f3294e317b181477276b653c8f53e11ce59c1d1a Mon Sep 17 00:00:00 2001
From: rrbharath <ryanrbharath@gmail.com>
Date: Tue, 28 Jul 2026 17:14:54 -0400
Subject: [PATCH] Add Dart solution for Binary Tree Preorder Traversal

---
 dart/binary_tree_preorder_traversal.dart | 31 ++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 dart/binary_tree_preorder_traversal.dart

diff --git a/dart/binary_tree_preorder_traversal.dart b/dart/binary_tree_preorder_traversal.dart
new file mode 100644
index 0000000..57fbfe0
--- /dev/null
+++ b/dart/binary_tree_preorder_traversal.dart
@@ -0,0 +1,31 @@
+/*
+Given the root of a binary tree, return the preorder traversal of its nodes' values.
+*/
+
+/*
+Definition for a binary tree node.
+class TreeNode {
+  int val;
+  TreeNode? left;
+  TreeNode? right;
+  TreeNode([this.val = 0, this.left, this.right]);
+}
+*/
+
+class Solution {
+  List<int> preorderTraversal(TreeNode? root) {
+    final List<int> ans = [];
+    preorder(root, ans);
+    return ans;
+  }
+
+  void preorder(TreeNode? root, List<int> ans) {
+    if (root == null) {
+      return;
+    }
+
+    ans.add(root.val);
+    preorder(root.left, ans);
+    preorder(root.right, ans);
+  }
+}