Add Two Numbers

Link

A bit tricky simply because they had test cases which required me to use long instead of int. I basically converted all the Nodes to ints, summed them up, and then converted it back into a linked list again. Nothing too fancy.

Full Solution in Java:

 /**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        
        long one = nodeToInt(l1);
        long two = nodeToInt(l2);
        
        long sum = one+two;
        
        if(sum==0){
            return new ListNode(0);
        }
        
        
        ListNode head = new ListNode(0);
        ListNode ret = head;
        while(sum>0){
            head.next = new ListNode((int)(sum%10));
            head = head.next;
            sum/=10;
        }
        return ret.next;
    }
    
    
    long nodeToInt(ListNode l){
        int i = 0;
        long ret = 0;
        while(l!=null){
            ret+=Math.pow(10,i)*l.val;
            i++;
            l = l.next;
        }
        return ret;
    }
}