挑战刷leetcode第二天（两数相加），你看我行吗？

java版本

 * 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 pre = new ListNode(0);
        ListNode tmp = pre;

        int cur = 0;
        while(l1!=null || l2!=null){
            int n1 = l1!=null?l1.val:0;
            int n2 = l2!=null?l2.val:0;
            int n = n1+n2+cur;
            cur = n/10;

            ListNode node = new ListNode(n%10);

            tmp.next = node;

            tmp = tmp.next;

            if(l1!=null){
                l1 = l1.next;
            }
            if(l2!=null){
                l2 = l2.next;
            }
        }
        if(cur!=0){
            tmp.next = new ListNode(cur);
        }
        return pre.next;
    }
}

C++版本

 * 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* pre = new ListNode(0);
        ListNode* tmp = pre;

        int cur = 0;
        while(l1!=nullptr || l2!=nullptr){
            int n1 = l1!=nullptr?l1->val:0;
            int n2 = l2!=nullptr?l2->val:0;
            int n = n1+n2+cur;
            cur = n/10;

            ListNode* node = new ListNode(n%10);

            tmp->next = node;

            tmp = tmp->next;

            if(l1!=nullptr){
                l1 = l1->next;
            }
            if(l2!=nullptr){
                l2 = l2->next;
            }
        }
        if(cur!=0){
            tmp->next = new ListNode(cur);
        }
        return pre->next;
    }
};

总结

核心点就是对不足的节点进行补0，这样会省掉很多边界的判断， 另外语言上，C++和java的实现方式基本相同，主要就是访问指针的差异

打卡完成，继续坚持！！！希望友友们监督哈