🐜 Study: Add Two Numbers

Author: ing-eoking

ing-eoking/Add Two Numbers.cc

@@ -0,0 +1,29 @@
+/**
+ * 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 *head = NULL, *tail = NULL;
+            int add = 0;
+            while (l1 != NULL or l2 != NULL or add > 0) {
+                ListNode *node = new ListNode(0, NULL);
+                int val = (l1 ? l1->val : 0) + (l2 ? l2->val : 0) + add;
+                node->val = val % 10;
+                add = val / 10;
+                if (l1) l1 = l1->next;
+                if (l2) l2 = l2->next;
+                if (!head) head = node;
+                else tail->next = node;
+                tail = node;
+            }
+            return head;
+        }
+    };