首页 > itarticle > leetcode 2. add two numbers

leetcode 2. add two numbers

admin 11月 12, 2020 0

2. Add Two Numbers

Difficulty: Medium

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.

Example:

1
2
3

**Input:** (2 -> 4 -> 3) + (5 -> 6 -> 4)
**Output:** 7 -> 0 -> 8
**Explanation:** 342 + 465 = 807.

Solution

Language: Java



 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class  {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode dummy = new ListNode(0);
        ListNode n1 = l1;
        ListNode n2 = l2;
        ListNode current = dummy;
        int carry = 0;
        
        while(n1 != null || n2 != null){
            int val1 = n1 == null? 0 : n1.val;
            int val2 = n2 == null? 0 : n2.val;
            int sum = val1 + val2 + carry;
            carry = sum / 10;
            current.next = new ListNode(sum % 10);
            current = current.next;
            if(n1 != null) n1 = n1.next;
            if(n2 != null) n2 = n2.next;
        }
        if(carry > 0){
            current.next = new ListNode(carry);
        }
        return dummy.next;
    }
}