Merge pull request #20 from fartem/94_Binary_Tree_Inorder_Traversal

2023-02-11 update: added "94. Binary Tree Inorder Traversal"

Author: fartem

README.md

@@ -29,3 +29,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 70. Climbing Stairs                    | [Link](https://leetcode.com/problems/climbing-stairs/)                    | [Link](./lib/easy/climbing_stairs.dart)                    |
 | 83. Remove Duplicates from Sorted List | [Link](https://leetcode.com/problems/remove-duplicates-from-sorted-list/) | [Link](./lib/easy/remove_duplicates_from_sorted_list.dart) |
 | 88. Merge Sorted Array                 | [Link](https://leetcode.com/problems/merge-sorted-array/)                 | [Link](./lib/easy/merge_sorted_array.dart)                 |
+| 94. Binary Tree Inorder Traversal      | [Link](https://leetcode.com/problems/binary-tree-inorder-traversal/)      | [Link](./lib/easy/binary_tree_inorder_traversal.dart)      |

lib/common/tree_node.dart

@@ -0,0 +1,11 @@
+class TreeNode {
+  int val;
+  TreeNode? left;
+  TreeNode? right;
+
+  TreeNode([
+    this.val = 0,
+    this.left,
+    this.right,
+  ]);
+}

lib/easy/binary_tree_inorder_traversal.dart

@@ -0,0 +1,18 @@
+// https://leetcode.com/problems/binary-tree-inorder-traversal/
+import '../common/tree_node.dart';
+
+class Solution {
+  List<int> inorderTraversal(TreeNode? root) {
+    final values = <int>[];
+    _apply(root, values);
+    return values;
+  }
+
+  void _apply(TreeNode? node, List<int> values) {
+    if (node != null) {
+      _apply(node.left, values);
+      values.add(node.val);
+      _apply(node.right, values);
+    }
+  }
+}

test/common/binary_tree_helper.dart

@@ -0,0 +1,15 @@
+import 'package:leetcode_dart/common/tree_node.dart';
+
+class LinkedListHelper {
+  LinkedListHelper._();
+
+  static bool areEqual(TreeNode? f, TreeNode? s) {
+    while (f != null && s != null) {
+      if (f.val != s.val) {
+        return false;
+      }
+      return areEqual(f.left, s.left) && areEqual(f.right, s.right);
+    }
+    return f == null && s == null;
+  }
+}

test/easy/binary_tree_inorder_traversal_test.dart

@@ -0,0 +1,30 @@
+import 'package:leetcode_dart/common/tree_node.dart';
+import 'package:leetcode_dart/easy/binary_tree_inorder_traversal.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group(
+    'Example tests',
+    () {
+      final btit = Solution();
+      test(
+        '[1, 3, 2]',
+        () => expect(
+          [1, 3, 2],
+          btit.inorderTraversal(
+            TreeNode(
+              1,
+              null,
+              TreeNode(
+                2,
+                TreeNode(3),
+              ),
+            ),
+          ),
+        ),
+      );
+      test('[]', () => expect([], btit.inorderTraversal(null)));
+      test('[1]', () => expect([1], btit.inorderTraversal(TreeNode(1))));
+    },
+  );
+}