[Leetcode 2/100] Add Two Numbers - Medium

https://leetcode.com/problems/add-two-numbers/

Add Two Numbers - LeetCode

(다시 풀기)

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        
        ListNode dummyHead = new ListNode(0);
        ListNode p = l1, q = l2, curr = dummyHead;
        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 dummyHead.next;
    }
}