Create 2816. Double a Number Represented as a Linked List (#473)

Author: Chayandas07

2816. Double a Number Represented as a Linked List

@@ -0,0 +1,34 @@
+class Solution {
+public:
+    ListNode* doubleIt(ListNode* head) {
+        // Initialize a stack to store the values of the linked list
+        stack<int> values;
+        int val = 0;
+
+        // Traverse the linked list and push its values onto the stack
+        while (head != nullptr) {
+            values.push(head->val);
+            head = head->next;
+        }
+
+        ListNode* newTail = nullptr;
+
+        // Iterate over the stack of values and the carryover
+        while (!values.empty() || val != 0) {
+            // Create a new ListNode with value 0 and the previous tail as its next node
+            newTail = new ListNode(0, newTail);
+            
+            // Calculate the new value for the current node
+            // by doubling the last digit, adding carry, and getting the remainder
+            if (!values.empty()) {
+                val += values.top() * 2;
+                values.pop();
+            }
+            newTail->val = val % 10;
+            val /= 10;
+        }
+
+        // Return the tail of the new linked list
+        return newTail;
+    }
+};