Add two numbers and return the answer in the form of reversed linked list.

src/main/java/com/thealgorithms/datastructures/lists/AddTwoNumbers.java

@@ -0,0 +1,54 @@
+package com.thealgorithms.datastructures.lists;
+
+// Given two numbers in the form of reversed linked list
+// Add two numbers and return the answer in the form of reversed linked list again.
+// Also known as the implementation of SumList
+
+class Node {
+    int data;
+    Node next;
+
+    public Node(int data) {
+        this.data = data;
+        this.next = null;
+    }
+}
+
+public class AddTwoNumbers {
+    public Node addTwoNumbers(Node head1, Node head2) {
+        if (head1 == null && head2 == null) {
+            return null;
+        }
+        Node temp1 = head1;
+        Node temp2 = head2;
+        Node dummy = new Node(-1);
+        Node temp = dummy;
+        int carry = 0;
+
+        while (temp1 != null || temp2 != null) {
+            int sum = carry;
+            if (temp1 != null) {
+                sum += temp1.data;
+            }
+            if (temp2 != null) {
+                sum += temp2.data;
+            }
+            Node newNode = new Node(sum % 10);
+            carry = sum / 10;
+            temp.next = newNode;
+            temp = temp.next;
+
+            if (temp1 != null) {
+                temp1 = temp1.next;
+            }
+            if (temp2 != null) {
+                temp2 = temp2.next;
+            }
+        }
+        if (carry != 0) {
+            Node currNode = new Node(carry);
+            temp.next = currNode;
+        }
+        return dummy.next;
+    }
+}