add-two-numbers-en.java

package java;


// Definition for singly-linked list.
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 AddTwoNumbersEn {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode ans = new ListNode(0);
        ListNode dummy = ans;
        int c = 0;
        while (l1 != null && l2 != null) {
            int sum = l1.val + l2.val + c;
            c = sum / 10;
            sum = sum % 10;
            ans.next = new ListNode(sum);
            ans = ans.next;
            l1 = l1.next;
            l2 = l2.next;
        }
        while (l1 != null) {
            int sum = l1.val + c;
            c = sum / 10;
            sum = sum % 10;
            ans.next = new ListNode(sum);
            ans = ans.next;
            l1 = l1.next;
        }
        while (l2 != null) {
            int sum = l2.val + c;
            c = sum / 10;
            sum = sum % 10;
            ans.next = new ListNode(sum);
            ans = ans.next;
            l2 = l2.next;
        }
        if (c > 0) {
            ans.next = new ListNode(c);
        }
        return dummy.next;
    }
}