### Add two numbers represented as Linked List - The Coding Shala

Home >> Interview Questions >> Add two numbers represented as linked list

Problem: You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contains a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

Approach 1:
Check carry at the end and check if the length is not the same for the linked list.

Java Code

```/**
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
int carry = 0;
ListNode ans = new ListNode(0);
ListNode dummy = ans;
while(l1 != null || l2 != null){
int val1 = 0;
int val2 = 0;
if(l1 != null){
val1 = l1.val;
l1 = l1.next;
}else{
val1 = 0;
}
if(l2 != null){
val2 = l2.val;
l2 = l2.next;
}else{
val2 = 0;
}
int tt = val1 + val2 + carry;
if(tt > 9){
tt = tt%10;
carry =1;
}else carry =0;
ListNode tmp = new ListNode(tt);
dummy.next = tmp;
dummy = dummy.next;
}
if(carry >0){
ListNode tmp = new ListNode(1);
dummy.next = tmp;
dummy = dummy.next;
}
return ans.next;
}
}
```

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