<p>You are given two <strong>non-empty</strong> linked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.</p>

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

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/04/09/sumii-linked-list.jpg" style="width: 523px; height: 342px;" />
<pre>
<strong>Input:</strong> l1 = [7,2,4,3], l2 = [5,6,4]
<strong>Output:</strong> [7,8,0,7]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> l1 = [2,4,3], l2 = [5,6,4]
<strong>Output:</strong> [8,0,7]
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> l1 = [0], l2 = [0]
<strong>Output:</strong> [0]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in each linked list is in the range <code>[1, 100]</code>.</li>
	<li><code>0 &lt;= Node.val &lt;= 9</code></li>
	<li>It is guaranteed that the list represents a number that does not have leading zeros.</li>
</ul>

<p>&nbsp;</p>
<p><strong>Follow up:</strong>&nbsp;Could you solve it without reversing the input lists?</p>

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
     ListNode* reverese(ListNode* head)
{
    ListNode* prev=NULL;
    ListNode* curr= head;
    ListNode* temp;
    while(curr)
    {
        temp= curr->next;
        curr->next= prev;
        prev= curr; 
        curr= temp;
    }
    return prev;
}
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* x= reverese(l1);
        ListNode* y= reverese(l2);
        ListNode* dummy = new ListNode();
        ListNode* head= dummy; 
        int carry=0 ; 
        while(x and y)
        {
             int s = x->val +y->val +carry ;
            x->val = s%10;
            carry= s/10;
            dummy->next= x;
            dummy= dummy->next;
            x= x->next;
            y= y->next;
        }
         while(x)
        {
            int s= x->val +carry;
            x->val= s%10;
            carry= s/10;
            dummy->next= x;
            dummy= dummy->next;
            x=x->next;
        }
        while(y)
        {
            int s= y->val +carry;
            y->val= s%10;
            carry= s/10;
            dummy->next= y;
            dummy= dummy->next;
            y=y->next;
        }
        if(carry)
        {
            ListNode* lauda = new ListNode(1);
            dummy->next=lauda;
            dummy= dummy->next;
        }
        dummy->next = NULL;
        ListNode* res= reverese(head->next);
        return res;

    }
};
76800