import datastructs.ListNode;

import java.util.List;

public class Q2AddTwoNumbers {

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

var rl1 = reverse(l1);

var rl2 = reverse(l2);

System.out.println(rl1.printAsList());

System.out.println(rl2.printAsList());

var dummyHead = new ListNode(0);

var cur = dummyHead;

var incr = 0;

while (rl1 != null || rl2 != null || incr != 0){

if (rl1 == null){

rl1 = new ListNode(0);

}

if (rl2 == null){

rl2 = new ListNode(0);

}

cur.next = new ListNode((rl1.val + rl2.val + incr) % 10);

incr = (rl1.val + rl2.val + incr) / 10;

rl1 = rl1.next;

rl2 = rl2.next;

cur = cur.next;

}

return reverse(dummyHead.next);

}

private ListNode reverse(ListNode head){

if (head == null || head.next == null){

return head;

}

ListNode prev = null;

ListNode cur = head;

while (cur != null) {

var next = cur.next;

cur.next = prev;

prev = cur;

cur = next;

}

return prev;

}

public static void main(String[] args) {

var l1 = new ListNode(List.of(2,4,3));

var l2 = new ListNode(List.of(5,6,4));

System.out.println(new Q2AddTwoNumbers().addTwoNumbers(l1, l2).printAsList());

}

}