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leetcode 2_addtwonumbers

admin 11月 12, 2020 0

Description

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

Solution

两个链表从头到尾相加即可，但是需要记录进位。

/**
 * 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) {
        int extra = 0;
        ListNode head(0), *p = &head;
        while(l1 || l2 || extra){
            int a = (l1?l1->val:0) + (l2?l2->val:0) + extra;
            extra = a /10;
            p->next = new ListNode(a%10);
            p = p->next;
            l1 = l1->next?l1->next:NULL;
            l2 = l2->next?l2->next:NULL;
        }
        return head.next;
    }
};