@@ -25,6 +25,8 @@ Output: 7 -> 8 -> 0 -> 7
2525
2626最后根据stack生成最终的链表即可。
2727
28+ > 也可以先将两个链表逆置,然后相加,最后将结果再次逆置。
29+
2830## 关键点解析
2931
3032- 栈的基本操作
@@ -33,6 +35,10 @@ Output: 7 -> 8 -> 0 -> 7
3335- 注意特殊情况, 比如 1 + 99 = 100
3436
3537## 代码
38+ * 语言支持:JS,C++
39+ 40+ JavaScript Code:
41+ 3642``` js
3743/*
3844 * @lc app=leetcode id=445 lang=javascript
@@ -135,3 +141,97 @@ var addTwoNumbers = function(l1, l2) {
135141};
136142
137143```
144+ C++ Code:
145+ ``` C++
146+ /* *
147+ * Definition for singly-linked list.
148+ * struct ListNode {
149+ * int val;
150+ * ListNode *next;
151+ * ListNode(int x) : val(x), next(NULL) {}
152+ * };
153+ */
154+ class Solution {
155+ public:
156+ ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
157+ auto carry = 0;
158+ auto ret = (ListNode* )nullptr;
159+ auto s1 = vector<int >();
160+ toStack(l1, s1);
161+ auto s2 = vector<int >();
162+ toStack(l2, s2);
163+ while (!s1.empty() || !s2.empty() || carry != 0) {
164+ auto v1 = 0;
165+ auto v2 = 0;
166+ if (!s1.empty()) {
167+ v1 = s1.back();
168+ s1.pop_back();
169+ }
170+ if (!s2.empty()) {
171+ v2 = s2.back();
172+ s2.pop_back();
173+ }
174+ auto v = v1 + v2 + carry;
175+ carry = v / 10;
176+ auto tmp = new ListNode(v % 10);
177+ tmp->next = ret;
178+ ret = tmp;
179+ }
180+ return ret;
181+ }
182+ private:
183+ // 此处若返回而非传入vector,跑完所有测试用例多花8ms
184+ void toStack(const ListNode* l, vector<int >& ret) {
185+ while (l != nullptr) {
186+ ret.push_back(l->val);
187+ l = l->next;
188+ }
189+ }
190+ };
191+ 192+ // 逆置,相加,再逆置。跑完所有测试用例比第一种解法少花4ms
193+ class Solution {
194+ public:
195+ ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
196+ auto rl1 = reverseList(l1);
197+ auto rl2 = reverseList(l2);
198+ auto ret = add(rl1, rl2);
199+ return reverseList(ret);
200+ }
201+ private:
202+ ListNode* reverseList(ListNode* head) {
203+ ListNode* prev = NULL;
204+ ListNode* cur = head;
205+ ListNode* next = NULL;
206+ while (cur != NULL) {
207+ next = cur->next;
208+ cur->next = prev;
209+ prev = cur;
210+ cur = next;
211+ }
212+ return prev;
213+ }
214+ 215+ ListNode* add(ListNode* l1, ListNode* l2) {
216+ ListNode* ret = nullptr;
217+ ListNode* cur = nullptr;
218+ int carry = 0;
219+ while (l1 != nullptr || l2 != nullptr || carry != 0) {
220+ carry += (l1 == nullptr ? 0 : l1->val) + (l2 == nullptr ? 0 : l2->val);
221+ auto temp = new ListNode(carry % 10);
222+ carry /= 10;
223+ if (ret == nullptr) {
224+ ret = temp;
225+ cur = ret;
226+ }
227+ else {
228+ cur->next = temp;
229+ cur = cur->next;
230+ }
231+ l1 = l1 == nullptr ? nullptr : l1->next;
232+ l2 = l2 == nullptr ? nullptr : l2->next;
233+ }
234+ return ret;
235+ }
236+ };
237+ ```
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