2. Add Two Numbers

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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 the sum as a linked list.

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

Example 1:

Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.

Example 2:

Input: l1 = [0], l2 = [0]
Output: [0]

Example 3:

Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]

Constraints:

• The number of nodes in each linked list is in the range [1, 100].
• 0 <= Node.val <= 9
• It is guaranteed that the list represents a number that does not have leading zeros.

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        int carry=0;
        ListNode fir=l1, sec=l2, res=new ListNode(-1), curr=res;

        while(fir!=null && sec!=null){
            int sum= (fir.val+sec.val+carry);
            carry= sum/10;
            curr.next=new ListNode(sum%10);
            curr=curr.next;
            fir=fir.next;
            sec=sec.next;
        }

        while(fir!=null){
            int sum= (fir.val+carry);
            carry= sum/10;
            curr.next=new ListNode(sum%10);
            curr=curr.next;
            fir=fir.next;
        }


        while(sec!=null){
            int sum= (sec.val+carry);
            carry= sum/10;
            curr.next=new ListNode(sum%10);
            curr=curr.next;
            sec=sec.next;
        }

        if(carry!=0){
            curr.next=new ListNode(carry);
        }

        res=res.next;
        return res;
    }
}

/**
2. Add Two Numbers
Solved
Medium
Topics
Companies
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 the sum as a linked list.

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

 

Example 1:


Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.
Example 2:

Input: l1 = [0], l2 = [0]
Output: [0]
Example 3:

Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]

Constraints:

The number of nodes in each linked list is in the range [1, 100].
0 <= Node.val <= 9
It is guaranteed that the list represents a number that does not have leading zeros.
Seen this question in a real interview before?
1/5
Yes

 */