<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 {
    vector<int>sum1(vector<int>arr1,vector<int>arr2){
       vector<int>result;
        int n=arr1.size();
        int m=arr2.size();
        int i=n-1,j=m-1,carry=0,sum=0;
      while(i>=0 ||j>=0||carry){
        int sum=carry;
        if(i>=0)sum+=arr1[i--];
        if(j>=0)sum+=arr2[j--];
         result.push_back(sum%10);
        carry=sum/10;
      }
      reverse(result.begin(),result.end());
        return result;


    }
    public:
 ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
    if(l1->val==0 && l2->val==0)return l1;
    if(l1->val==0)return l2;
    if(l2->val==0)return l1;
    
      vector<int>arr1;
      vector<int>arr2;
      vector<int>sum;
      ListNode*temp1=l1;
      ListNode*temp2=l2;
      while(temp1!=NULL){
        arr1.push_back(temp1->val);
        temp1=temp1->next;
      }  
      while(temp2!=NULL){
        arr2.push_back(temp2->val);
        temp2=temp2->next;
      }  

      sum=sum1(arr1,arr2);
      ListNode*temp=new ListNode(sum[0]);
      ListNode*curr=temp;
      for(int i=1;i<sum.size();i++){
        curr->next=new ListNode(sum[i]);
        curr=curr->next;
      }


    return temp;
}
};

        

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