[LeetCode] 2. Add Two Numbers

1. 原题链接：https://leetcode.com/problems/add-two-numbers/

2. 解题思路

1. 两个链表相加的解题思路比较直接
2. 需要注意两个链表的长度不同，有些边界情况需要考虑周到
3. 考虑进位的情况

3. 算法

1. 首先，遍历两个链表长度相同的部分
2. 然后，遍历长度较长的链表

4. 实现

struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode header(-1);
        int value = 0;
        ListNode *prev = &header;
        while(l1 && l2){
            int v1 = l1->val;
            int v2 = l2->val;
            int sum = v1 + v2 + value;
            int current_value = sum % 10;
            value = sum / 10;
            prev->next = new ListNode(current_value);
            l1 = l1->next;
            l2 = l2->next;
            prev = prev->next;
        }
        while(l1){
            int v = l1->val;
            int sum = v + value;
            int current_value = sum % 10;
            value = sum / 10;
            prev->next = new ListNode(current_value);
            l1 = l1->next;
            prev = prev->next;
        }
        while(l2){
            int v = l2->val;
            int sum = v + value;
            int current_value = sum % 10;
            value = sum / 10;
            prev->next = new ListNode(current_value);
            l2 = l2->next;
            prev = prev->next;
        }
        if(value > 0){
            prev->next = new ListNode(value);
        }
        return header.next;
    }
};

来源：https://www.cnblogs.com/wengle520/p/12293196.html