2023-02-08 update: added "67. Add Binary"

README.md

@@ -24,3 +24,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 35. Search Insert Position | [Link](https://leetcode.com/problems/search-insert-position/) | [Link](./lib/easy/search_insert_position.dart) |
 | 58. Length of Last Word    | [Link](https://leetcode.com/problems/length-of-last-word/)    | [Link](./lib/easy/length_of_last_word.dart)    |
 | 66. Plus One               | [Link](https://leetcode.com/problems/plus-one/)               | [Link](./lib/easy/plus_one.dart)               |
+| 67. Add Binary             | [Link](https://leetcode.com/problems/add-binary/)             | [Link](./lib/easy/add_binary.dart)             |

lib/easy/add_binary.dart

@@ -0,0 +1,48 @@
+// https://leetcode.com/problems/add-binary/
+class Solution {
+  String addBinary(String a, String b) {
+    var max = a.length > b.length ? a : b;
+    var min = max == a ? b : a;
+    var maxP = max.length - 1;
+    var minP = min.length - 1;
+    var result = [];
+    var add = 0;
+    while (minP >= 0) {
+      var maxC = max[maxP];
+      var minC = min[minP];
+      if (add == 1) {
+        result.add(maxC == minC ? '1' : '0');
+        if (maxC == '0' && minC == '0') {
+          add = 0;
+        }
+      } else {
+        if (maxC == '1' && minC == '1') {
+          add = 1;
+          result.add('0');
+        } else {
+          result.add(maxC == '1' || minC == '1' ? '1' : '0');
+        }
+      }
+      maxP--;
+      minP--;
+    }
+    while (maxP >= 0) {
+      var maxC = max[maxP];
+      if (add == 1 && maxC == '1') {
+        result.add('0');
+      } else {
+        if (add == 1) {
+          result.add('1');
+          add = 0;
+        } else {
+          result.add(maxC);
+        }
+      }
+      maxP--;
+    }
+    if (add == 1) {
+      result.add('1');
+    }
+    return result.reversed.join();
+  }
+}

test/easy/add_binary_test.dart

@@ -0,0 +1,13 @@
+import 'package:leetcode_dart/easy/add_binary.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group(
+    'Example tests',
+    () {
+      final ab = Solution();
+      test('100', () => expect('100', ab.addBinary('11', '1')));
+      test('10101', () => expect('10101', ab.addBinary('1010', '1011')));
+    },
+  );
+}