You are given two non-empty linked lists representing two non-negative integers. 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.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8
/** * 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) { if (l1 == NULL && l2 != NULL) return l2; if (l1 != NULL && l2 == NULL) return l1; if (l1 == NULL && l2 == NULL) return NULL; ListNode *res; int temp = 0; if (l1 != NULL && l2 != NULL) { res = new ListNode((l1->val + l2->val) % 10); temp = (l1->val + l2->val) / 10; l1 = l1->next; l2 = l2->next; } ListNode *p = res; while (l1 != NULL && l2 != NULL) { ListNode *node = new ListNode((l1->val + l2->val + temp) % 10); temp = (l1->val + l2->val + temp) / 10; l1 = l1->next; l2 = l2->next; p->next = node; p = node; } while(l1 != NULL && l2 == NULL) { ListNode *node = new ListNode((l1->val + temp ) % 10); temp = (l1->val + temp) / 10; l1 = l1->next; p->next = node; p = node; } while (l2 != NULL && l1 == NULL) { ListNode *node = new ListNode((l2->val + temp) % 10); temp = (l2->val + temp) / 10; l2 = l2->next; p->next = node; p = node; } if (temp != 0) { ListNode *node = new ListNode(temp); p->next = node; } return res; } };