LeetCode刷题（C++）——Add Two Numbers（Medium）

客官°小女子只卖身不卖艺 2022-06-16 00:40 115阅读 0赞

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 NULL;
    		if (l1 == NULL)
    			return l2;
    		if (l2 == NULL)
    			return l1;
    		ListNode* p1 = l1;
    		ListNode* p2 = l2;
    		ListNode*newList = new ListNode(0);
    		ListNode* p = newList;
    		int a = 0;
    		while (p1 != NULL&&p2 != NULL)
    		{
    			a += p1->val + p2->val;
    			p->next = new ListNode(a % 10);
    			a /= 10;
    			p1 = p1->next;
    			p2 = p2->next;
    			p = p->next;
    		}
    		while (p1 != NULL)
    		{
    			a += p1->val;
    			p->next = new ListNode(a % 10);
    			a /= 10;
    			p1 = p1->next;
    			p = p->next;
    		}
    		while (p2 != NULL)
    		{
    			a += p2->val;
    			p->next = new ListNode(a % 10);
    			a /= 10;
    			p2 = p2->next;
    			p = p->next;
    		}
    		if (a)
    		{
    			p->next = new ListNode(a);
    			p = p->next;
    		}
    		return newList->next;
        }
    };