2.两数相加.java

/*
 * @lc app=leetcode.cn id=2 lang=java
 *
 * [2] 两数相加
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode l3 = new ListNode(0);
        ListNode p = l1;
        ListNode q = l2;
        ListNode curr = l3;
        int carry = 0;
        while(p != null || q != null){
            int x = (p != null)?p.val:0;
            int y = (q != null)?q.val:0;
            int sum = carry + x + y;
            carry = sum / 10;
            curr.next = new ListNode(sum % 10);
            curr = curr.next;
            if(p != null) p = p.next;
            if(q != null) q = q.next;
            
        }
        if(carry > 0){
            curr.next = new ListNode(carry);
        }
        return l3.next;//因为头节点为0
    }
}
// @lc code=end