add problem add_two_numbers

leetcode/src/problems.rs

@@ -1,3 +1,4 @@
+pub mod add_two_numbers;
 pub mod two_sum;
 
 #[allow(dead_code)]

leetcode/src/problems/add_two_numbers.rs

@@ -0,0 +1,28 @@
+use super::{Difficulty, Problem, Topic};
+
+pub struct AddTwoNumbers;
+
+impl Problem for AddTwoNumbers {
+    fn id(&self) -> usize {
+        2
+    }
+    fn difficulty(&self) -> Difficulty {
+        Difficulty::Medium
+    }
+    fn topic(&self) -> Topic {
+        Topic::Algorithms
+    }
+    fn title(&self) -> String {
+        "Add Two Numbers".into()
+    }
+    fn description(&self) -> String {
+        r#"You are given two non-empty linked lists representing two non-negative integers.
+The digits are stored in reverse order, and each of their nodes contains a single digit.
+Add the two numbers and return the sum as a linked list.
+You may assume the two numbers do not contain any leading zero, except the number 0 itself."#
+            .into()
+    }
+    fn labels(&self) -> Vec<String> {
+        ["link list".into()].into()
+    }
+}