2023-02-09 update: added "70. Climbing Stairs"

Author: fartem

README.md

@@ -26,3 +26,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 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)             |
 | 69. Sqrt(x)                | [Link](https://leetcode.com/problems/sqrtx/)                  | [Link](./lib/easy/sqrt_x.dart)                 |
+| 70. Climbing Stairs        | [Link](https://leetcode.com/problems/climbing-stairs/)        | [Link](./lib/easy/climbing_stairs.dart)        |

lib/easy/climbing_stairs.dart

@@ -0,0 +1,16 @@
+// https://leetcode.com/problems/climbing-stairs/
+class Solution {
+  int climbStairs(int n) {
+    if (n == 1) {
+      return 1;
+    }
+    var n1 = 1;
+    var n2 = 2;
+    for (var i = 3; i <= n; i++) {
+      var temp = n1;
+      n1 = n2;
+      n2 += temp;
+    }
+    return n2;
+  }
+}

test/easy/climbing_stairs_test.dart

@@ -0,0 +1,13 @@
+import 'package:leetcode_dart/easy/climbing_stairs.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group(
+    'Example tests',
+    () {
+      final cs = Solution();
+      test('2', () => expect(2, cs.climbStairs(2)));
+      test('3', () => expect(3, cs.climbStairs(3)));
+    },
+  );
+}