CODE 126: Add Two Numbers

You are given two linked lists representing two non-negative numbers. 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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)

Output: 7 -> 0 -> 8

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
// Start typing your Java solution below
// DO NOT write main() function
ListNode cpyl1 = l1;
ListNode cpyl2 = l2;
int c = 0;
while (null != cpyl1 && null != cpyl2) {
int tmp = cpyl1.val + cpyl2.val + c;
if (tmp > 9) {
c = tmp / 10;
}
cpyl1.val = tmp % 10;
cpyl1 = cpyl1.next;
cpyl2 = cpyl2.next;
}
while (cpyl1 != null) {
int tmp = cpyl1.val + c;
if (tmp > 9) {
c = tmp / 10;
}
cpyl1.val = tmp % 10;
cpyl1 = cpyl1.next;
}
cpyl1 = l1;
while (null != cpyl1.next) {
cpyl1 = cpyl1.next;
}

while (cpyl2 != null) {
int tmp = cpyl2.val + c;
if (tmp > 9) {
c = tmp / 10;
}
cpyl1.next = new ListNode(tmp % 10);
cpyl1 = cpyl1.next;
cpyl2 = cpyl2.next;
}
if (c != 0) {
cpyl1.next = new ListNode(c);
}
return l1;
}