add task 2

2. Add Two Numbers/Solution.java

@@ -0,0 +1,36 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
+      ListNode dummy = new ListNode();
+      var cur = dummy;
+
+      int carry = 0;
+
+      while (carry != 0 || l1 != null || l2 != null) {
+        int v1 = (l1 != null) ? l1.val : 0;
+        int v2 = (l2 != null) ? l2.val : 0;
+
+        int val = v1 + v2 + carry;
+        carry = val / 10;
+        val = val % 10;
+
+        cur.next = new ListNode(val);
+
+        cur = cur.next;
+
+        l1 = (l1 != null) ? l1.next : null;
+        l2 = (l2 != null) ? l2.next : null;
+      }
+
+      return dummy.next;
+    }
+}