feat: add question #449

Author: hi-dhl

.gitignore

@@ -271,4 +271,5 @@ captures/
 *.DS_Store
 
 .MWebMetaData/
-gradle.properties
+gradle.properties
+cmake-build-debug/

code/_445/Solution.cpp

@@ -30,7 +30,7 @@ class Solution {
         ListNode *p2 = reverse(l2);
         int carry = 0;
         ListNode *head = nullptr;
-        while ((p1 || p2)) {
+        while (p1 || p2 || carry > 0) {
             int a = p1 ? p1->val : 0;
             int b = p2 ? p2->val : 0;
             int sum = a + b + carry;

code/_445/Solution2.cpp

@@ -0,0 +1,44 @@
+//
+// Created by DHL on 2022/4/29.
+//
+
+/**
+ * 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 Solution2 {
+public:
+    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
+        stack<int> stack1, stack2;
+        while (l1) {
+            stack1.push(l1->val);
+            l1 = l1->next;
+        }
+
+        while (l2) {
+            stack2.push(l2->val);
+            l2 = l2->next;
+        }
+        int carry = 0;
+        ListNode *head = nullptr;
+        while (!stack1.empty() || !stack2.empty() || carry > 0) {
+            int a = !stack1.empty() ? stack1.top() : 0;
+            int b = !stack2.empty() ? stack2.top() : 0;
+            int sum = a + b + carry;
+            carry = sum / 10;
+            ListNode *node = new ListNode(sum % 10);
+            node->next = head;
+            head = node;
+            if (!stack1.empty()) stack1.pop();
+            if (!stack2.empty()) stack2.pop();
+        }
+        return head;
+    }
+
+};