<p>You are given the <code>head</code> of a <strong>non-empty</strong> linked list representing a non-negative integer without leading zeroes.</p>

<p>Return <em>the </em><code>head</code><em> of the linked list after <strong>doubling</strong> it</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2023/05/28/example.png" style="width: 401px; height: 81px;" />
<pre>
<strong>Input:</strong> head = [1,8,9]
<strong>Output:</strong> [3,7,8]
<strong>Explanation:</strong> The figure above corresponds to the given linked list which represents the number 189. Hence, the returned linked list represents the number 189 * 2 = 378.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2023/05/28/example2.png" style="width: 401px; height: 81px;" />
<pre>
<strong>Input:</strong> head = [9,9,9]
<strong>Output:</strong> [1,9,9,8]
<strong>Explanation:</strong> The figure above corresponds to the given linked list which represents the number 999. Hence, the returned linked list reprersents the number 999 * 2 = 1998. 
</pre>

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

<ul>
	<li>The number of nodes in the list is in the range <code>[1, 10<sup>4</sup>]</code></li>
	<li><font face="monospace"><code>0 &lt;= Node.val &lt;= 9</code></font></li>
	<li>The input is generated such that the list represents a number that does not have leading zeros, except the number <code>0</code> itself.</li>
</ul>

/**
 * 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:
    void makeDouble(string&s){
        string temp="";
        int carry=0;
        for(int i=s.size()-1;i>=0;i--){
            int digit=s[i]-'0';
            digit=digit+digit+carry;
            // cout<<digit<<"  ";
            carry=digit/10;
            temp+=(digit%10)+'0';
            // cout<<temp<<endl;

        }
        if(carry){
            temp+=carry+'0';
        }
        reverse(temp.begin(),temp.end());
        s=temp;
    }
    ListNode* doubleIt(ListNode* head) {
        string s="";
        ListNode*temp=head;

        while(temp!=NULL){
            s+=temp->val+'0';
            temp=temp->next;
            // num/=10;
        }
                // cout<<s<<endl;
        makeDouble(s);
        // s=to_string(stol(s)*2);
        // cout<<num;
        // num=num*2;
        // cout<<" "<<num;
        // string s=to_string(num);

        // reverse(s.begin(),s.end());
        // cout<<s;
        ListNode*newLL=new ListNode(s[0]-'0');
        head=newLL;
        for(int i=1;i<s.size();i++){
            newLL->next=new ListNode(s[i]-'0');
            newLL=newLL->next;
        }

        return head;
        
    }
};
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