New tasks

2. Add Two Numbers/Solution.cs

@@ -0,0 +1,40 @@
+namespace _2._Add_Two_Numbers;
+
+public class Solution {
+    public ListNode AddTwoNumbers(ListNode? l1, ListNode? l2)
+    {
+        ListNode? answer = null;
+        ListNode? answerEnd = answer;
+        int toNext = 0;
+        while (l1!=null || l2!=null)
+        {
+            int sum = 0;
+            if (l1 != null)
+            {
+                sum += l1.val;
+                l1 = l1.next;
+            }
+            if (l2 != null)
+            {
+                sum += l2.val;
+                l2 = l2.next;
+            }
+
+            sum += toNext;
+            toNext = sum / 10;
+            sum %= 10;
+            ListNode item = new ListNode(sum);
+            if (answer == null)
+                answer = answerEnd = item;
+            else
+            {
+                answerEnd.next = item;
+                answerEnd = item;
+            }
+        }
+
+        if (toNext != 0)
+            answerEnd.next = new ListNode(toNext);
+        return answer;
+    }
+}