add-two-numbers-ii

package com.company;

import java.util.*;

class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}
class Solution {

ListNode addTwo(ListNode l1, ListNode l2) {
//System.out.printf("add two %d, %d \n", l1.val, l2.val);
ListNode ret = new ListNode(l1.val + l2.val);
if (l1.next != null && l2.next != null) {
ret.next = addTwo(l1.next, l2.next);
ret.val += ret.next.val / 10;
ret.next.val = ret.next.val % 10;
}
else {
ret.next = null;
}
return ret;
}

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
int l1len = 0;
ListNode ln = l1;
while (ln != null) {
l1len++;
ln = ln.next;
}
int l2len = 0;
ln = l2;
while (ln != null) {
l2len++;
ln = ln.next;
}
if (l1len < l2len) {
ln = l1;
l1 = l2;
l2 = ln;
l1len = l1len ^ l2len;
l2len = l1len ^ l2len;
l1len = l1len ^ l2len;
}

for (int i=0; i<l1len-l2len; i++) {
ln = new ListNode(0);
ln.next = l2;
l2 = ln;
}

ln = addTwo(l1, l2);
if (ln.val >= 10) {
ListNode newHead = new ListNode(ln.val / 10);
ln.val = ln.val % 10;
newHead.next = ln;
ln = newHead;
}
return ln;
}
}

public class Main {

public static void main(String[] args) {
System.out.println("Hello!");
Solution solution = new Solution();

ListNode l1 = new ListNode(7);
ListNode l11 = new ListNode(2);
ListNode l12 = new ListNode(4);
ListNode l13 = new ListNode(3);
l1.next = l11;
l11.next = l12;
l12.next = l13;
ListNode l2 = new ListNode(5);
ListNode l21 = new ListNode(6);
ListNode l22 = new ListNode(4);
l2.next = l21;
l21.next = l22;
ListNode ret = solution.addTwoNumbers(l1, l2);
System.out.printf("Get ret: \n");
while (ret != null) {
System.out.printf("%d", ret.val);
ret = ret.next;
}
System.out.println();

/*Iterator<List<Integer>> iterator = ret.iterator();
while (iterator.hasNext()) {
Iterator iter = iterator.next().iterator();
while (iter.hasNext()) {
System.out.printf("%d,", iter.next());
}
System.out.println();
}*/

System.out.println();

}
}