LeetCode2. Add Two Numbers

題目介紹

原題鏈接：https://leetcode-cn.com/problems/add-two-numbers

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.

Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

解題方案

注意最高位相加之後可能有進位的情況。

class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* head = new ListNode(0);
        ListNode* cur = head;
        int carry = 0;
        while(l1!=NULL || l2!=NULL){
            int temp = carry;
            if(l1!=NULL){
                temp += l1->val;
                l1 = l1->next;
                
            }
             if(l2!=NULL){
                temp += l2->val;
                l2 = l2->next;
               }
            carry = temp/10;
            cur->next = new ListNode(temp%10);
            cur = cur->next;
        }
        if(carry == 1){
            cur->next = new ListNode(1);
        }
        return head->next;
    }
};