LeetCode题解：Add Two Numbers

Add Two Numbers

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

思路：

中小学竞赛题。

题解：

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {        ListNode* i1 = l1;        ListNode* i2 = l2;                ListNode* ret = new ListNode(0);        ListNode* ret_last = ret;                bool carry = false;                while(i1 != nullptr || i2 != nullptr)        {            int s = 0;            if (i1 != nullptr)                s = i1->val, i1 = i1->next;                        if (i2 != nullptr)                s += i2->val, i2 = i2->next;                        s += carry;            ret_last->next = new ListNode(s % 10);            ret_last = ret_last->next;            carry = (s >= 10);        }                if (carry)            ret_last->next = new ListNode(1);                ret_last = ret->next;        delete ret;                return ret_last;    }};