leetcode 2. Add Two Numbers

You are given two linked lists representing two non-negative numbers. 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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

342 + 465 = 807.链表模拟加法.

考虑进位.

public class A2AddTwoNumbers {public ListNode addTwoNumbers(ListNode l1, ListNode l2) {int sum,x,y;ListNode l3 = new ListNode(0);ListNode first = l3;// 进位int c = 0;while(l1 != null || l2 != null) {x = y = 0;if(l1 != null) {x = l1.val;l1 = l1.next;}if(l2 != null) {y = l2.val;l2 = l2.next;}sum = x + y + c;l3.next = new ListNode(sum % 10);l3 = l3.next;c = sum / 10;}if(c != 0) {l3.next = new ListNode(c);}return first.next;}}class ListNode {int val;ListNode next;ListNode(int x) {val = x;}}