<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) {
        ListNode* prev=nullptr,*next=nullptr,*cur=l1;
        //Reversing the linked list
        while(cur!=nullptr){
            next=cur->next;
            cur->next=prev;
            prev=cur;
            cur=next;
        }
        ListNode* prev2=nullptr,*next2=nullptr,*cur2=l2;
        //Reversing the linked list
        while(cur2!=nullptr){
            next2=cur2->next;
            cur2->next=prev2;
            prev2=cur2;
            cur2=next2;
        }
        //Adding two numbers
        int sum=0,c=0;
        ListNode* l3=nullptr;
        ListNode* temp=prev;
        ListNode* temp2=l3;
        while(prev || prev2){
            int val1=(prev!=nullptr)?prev->val:0;
            int val2=(prev2!=nullptr)?prev2->val:0;
            sum=(val1 + val2 + c)%10;
            c=(val1 + val2 + c)/10;
            if(prev)
            prev=prev->next;
            if(prev2)
            prev2=prev2->next;
            if(l3==nullptr){
                l3=new ListNode(sum);
                temp2=l3;
                continue;
            }
            temp2->next=new ListNode(sum);
            temp2=temp2->next;
        }
        if(c==1){
            temp2->next=new ListNode(1);
        }
        //Again reversing it
        prev=nullptr;
        next=nullptr,cur=l3;
        while(cur!=nullptr){
            next=cur->next;
            cur->next=prev;
            prev=cur;
            cur=next;
        }
        return prev;
    }
};
77000