<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* addTwoNumbers(ListNode* l1, ListNode* l2) {
        vector<int>nums1;vector<int>nums2;
        while(l1){
            nums1.push_back(l1->val);l1=l1->next;
        }
        while(l2){
            nums2.push_back(l2->val);l2=l2->next;
        }
        vector<int>rev1;vector<int>rev2;
        for(int i=nums1.size()-1;i>=0;i--)rev1.push_back(nums1[i]);
        for(int i=nums2.size()-1;i>=0;i--)rev2.push_back(nums2[i]);
        int n=max(nums1.size(),nums2.size());
        while(rev1.size()<=n)rev1.push_back(0);
        while(rev2.size()<=n)rev2.push_back(0);
        for(int i=0;i<rev1.size()-1;i++)
        {
            rev1[i]+=rev2[i];
            if(rev1[i]>9){rev1[i]%=10;rev1[i+1]++;}
        }
        if(rev1[rev1.size()-1]==0)rev1.pop_back();
        ListNode*temp=new ListNode();l1=temp;
        for(int i=rev1.size()-1;i>=0;i--)
        {

            ListNode*t=new ListNode(rev1[i]);temp->next=t;temp=t;
           
        }

        return l1->next;



    }
};
79000