Add two numbers represented as Linked List - The Coding Shala

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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.

Add two numbers represented as Linked List Java Program

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

Java Code 

/**
 * Definition for singly-linked list.
 * 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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