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Add Two Numbers

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.


Solution:

class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode result = new ListNode(0);
        ListNode p1 = l1; 
        ListNode p2 = l2;
        ListNode curr = result;
        int carry=0;
        while(p1!=null || p2!=null)
        {
            int x = (p1!=null)?p1.val:0;
            int y = (p2!=null)?p2.val:0;
            int sum = carry+x+y;
            carry = sum/10;
            curr.next = new ListNode(sum%10);
            curr=curr.next;
            if(p1!=null) p1=p1.next;
            if(p2!=null) p2=p2.next;
        }
        if(carry>0)
        {
            curr.next = new ListNode(carry);
        }
        return result.next;
    }
}


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