updated "203. Remove Linked List Elements"

Author: fluttermiddlepodcast

README.md

@@ -12,6 +12,7 @@ Solutions from [LeetCode](https://leetcode.com) on Dart.
 | 136. Single Number                          | [Link](https://leetcode.com/problems/single-number/)                         | [Link](./lib/easy/single_number.dart)                         |
 | 144. Binary Tree Preorder Traversal         | [Link](https://leetcode.com/problems/binary-tree-preorder-traversal/)        | [Link](./lib/easy/binary_tree_preorder_traversal.dart)        |
 | 169. Majority Element                       | [Link](https://leetcode.com/problems/majority-element/)                      | [Link](./lib/easy/majority_element.dart)                      |
+| 203. Remove Linked List Elements            | [Link](https://leetcode.com/problems/remove-linked-list-elements/)           | [Link](./lib/easy/remove_linked_list_elements.dart)           |
 | 217. Contains Duplicate                     | [Link](https://leetcode.com/problems/contains-duplicate/)                    | [Link](./lib/easy/contains_duplicate.dart)                    |
 | 226. Invert Binary Tree                     | [Link](https://leetcode.com/problems/invert-binary-tree/)                    | [Link](./lib/easy/invert_binary_tree.dart)                    |
 | 342. Power of Four                          | [Link](https://leetcode.com/problems/power-of-four/)                         | [Link](./lib/easy/power_of_four.dart)                         |

lib/easy/remove_linked_list_elements.dart

@@ -0,0 +1,23 @@
+class Solution {
+  ListNode? removeElements(ListNode? head, int val) {
+    while (head != null && head.val == val) {
+      head = head.next;
+    }
+    var curr = head;
+    while (curr != null && curr.next != null) {
+      if (curr.next!.val == val) {
+        curr.next = curr.next!.next;
+      } else {
+        curr = curr.next;
+      }
+    }
+    return head;
+  }
+}
+
+class ListNode {
+  int val;
+  ListNode? next;
+
+  ListNode([this.val = 0, this.next]);
+}

test/easy/remove_linked_list_elements_test.dart

@@ -0,0 +1,71 @@
+import 'package:leetcode_dart/easy/remove_linked_list_elements.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group(
+    'Example tests',
+    () {
+      final rlle = Solution();
+      test(
+        '[1, 2, 3, 4, 5]',
+        () => expect(
+          true,
+          _areEqual(
+            _fromList([1, 2, 3, 4, 5]),
+            rlle.removeElements(
+              _fromList([1, 2, 6, 3, 4, 5, 6]),
+              6,
+            ),
+          ),
+        ),
+      );
+      test(
+        '[]',
+        () => expect(
+          true,
+          _areEqual(
+            null,
+            rlle.removeElements(
+              null,
+              1,
+            ),
+          ),
+        ),
+      );
+      test(
+        '[]',
+        () => expect(
+          true,
+          _areEqual(
+            null,
+            rlle.removeElements(
+              _fromList([7, 7, 7, 7]),
+              7,
+            ),
+          ),
+        ),
+      );
+    },
+  );
+}
+
+ListNode _fromList(List<int> list) {
+  final head = ListNode(list.first);
+  var p = head;
+  for (int i = 1; i < list.length; i++) {
+    p.next = ListNode(list[i]);
+    p = p.next!;
+  }
+  return head;
+}
+
+bool _areEqual(ListNode? f, ListNode? s) {
+  while (f != null && s != null) {
+    if (f.val != s.val) {
+      return false;
+    }
+    f = f.next;
+    s = s.next;
+  }
+  return f == null && s == null;
+}