2、Add Two Numbers
You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse orderand 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.
思路
从两个链表头开始,逐个相加,记录进位符。注意如果最后一个是进位的话,还要新建一个node。
c++11
/**
* 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* res = new ListNode(-1);
ListNode* cur = res;
int bit = 0;
while (l1 || l2) {
int val1 = l1 ? l1->val : 0;
int val2 = l2 ? l2->val : 0;
int sum = val1 + val2 + bit;
bit = sum / 10;
cur->next = new ListNode(sum % 10);
cur = cur->next;
if (l1) l1 = l1->next;
if (l2) l2 = l2->next;
}
if (bit) cur->next = new ListNode(bit);
return res->next;
}
};
AC结果:
Runtime: 40 ms, faster than 96.43% of C++ online submissions for Add Two Numbers.
Memory Usage: 19.1 MB, less than 68.07% of C++ online submissions for Add Two Numbers.