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;
+    }
+}

2. Add Two Numbers/solution.cpp

@@ -0,0 +1,34 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode() : val(0), next(nullptr) {}
+ *     ListNode(int x) : val(x), next(nullptr) {}
+ *     ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
+        ListNode* dummy = new ListNode(0);
+        ListNode* cur = dummy;
+        int carry = 0;
+
+        while (l1 != nullptr || l2 != nullptr || carry != 0) {
+            int v1 = (l1 != nullptr) ? l1->val : 0;
+            int v2 = (l2 != nullptr) ? l2->val : 0;
+
+            int sum = v1 + v2 + carry;
+            carry = sum / 10;
+
+            cur->next = new ListNode(sum % 10);
+            cur = cur->next;
+
+            if (l1 != nullptr) l1 = l1->next;
+            if (l2 != nullptr) l2 = l2->next;
+        }
+
+        return dummy->next;
+    }
+};

2. Add Two Numbers/solution.py

@@ -0,0 +1,26 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:
+        dummy = ListNode()
+        cur = dummy 
+
+        carry = 0
+        while l1 or l2 or carry:
+            v1 = l1.val if l1 else 0
+            v2 = l2.val if l2 else 0
+
+            val = v1 + v2 + carry 
+
+            carry = val // 10
+            val = val % 10 
+            cur.next = ListNode(val)
+
+            cur = cur.next
+            l1 = l1.next if l1 else None
+            l2 = l2.next if l2 else None
+
+        return dummy.next