<p>Given an integer array <code>queries</code> and a <strong>positive</strong> integer <code>intLength</code>, return <em>an array</em> <code>answer</code> <em>where</em> <code>answer[i]</code> <em>is either the </em><code>queries[i]<sup>th</sup></code> <em>smallest <strong>positive palindrome</strong> of length</em> <code>intLength</code> <em>or</em> <code>-1</code><em> if no such palindrome exists</em>.</p>

<p>A <strong>palindrome</strong> is a number that reads the same backwards and forwards. Palindromes cannot have leading zeros.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> queries = [1,2,3,4,5,90], intLength = 3
<strong>Output:</strong> [101,111,121,131,141,999]
<strong>Explanation:</strong>
The first few palindromes of length 3 are:
101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, ...
The 90<sup>th</sup> palindrome of length 3 is 999.
</pre>

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

<pre>
<strong>Input:</strong> queries = [2,4,6], intLength = 4
<strong>Output:</strong> [1111,1331,1551]
<strong>Explanation:</strong>
The first six palindromes of length 4 are:
1001, 1111, 1221, 1331, 1441, and 1551.
</pre>

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

<ul>
	<li><code>1 &lt;= queries.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>1 &lt;= queries[i] &lt;= 10<sup>9</sup></code></li>
	<li><code>1 &lt;= intLength&nbsp;&lt;= 15</code></li>
</ul>

class Solution {
public:
     vector<long long> kthPalindrome(vector<int>& queries, int intLength) {
           vector<long long> result;
        long long start =  pow(10, (intLength+1)/2 - 1) ;
        
        for(int q: queries) { 
            string s = to_string(start + q - 1);
            string palindrome = s;
            reverse(s.begin(), s.end());
            if(intLength % 2 == 0) {
                palindrome += s;
            } else {
                palindrome += s.substr(1, s.size() - 1);
            }
			
			// len of palindrome should be intLength, otherwise -1
            if (palindrome.size() == intLength)
                result.push_back(stoll(palindrome));
            else
                result.push_back(-1);
        }
        
        return result;
    }
};
//      bool isPalindrome(long long x) {
        
        
//         string s=to_string(x);
        
//         int n=s.length();
//         int st=0,e=n-1;
//         while(st<=e)
//         {
//             if(s[st]!=s[e])
//                 return false;
//             else
//             {
//                 st++;
//                 e--;
//             }
//         }
//         return true;
//     }
//     vector<long long> kthPalindrome(vector<int>& queries, int intLength) {
//         int num=pow(10,intLength-1);
//         int end=pow(10,intLength)-1;
//         vector<long long> ans;
//         vector<long long> v;
//         int ct=1;
//         for(int i=num;i<=end;i++)
//         {
//             if(isPalindrome(i))
//             {
//                 if(find(queries.begin(),queries.end(),ct))
//                 {
//                     ans.push_back(i);
                    
//                 }
//                 ct++;
//             }
//         }
// //         int n=queries.size();
        
// //         for(int i=0;i<n;i++)
// //         {
// //             if(v.size()>=queries[i])
// //             ans.push_back(v[queries[i]-1]);
            
// //             else
// //                 ans.push_back(-1);;
// //         }
        
//         return ans;
        
        
//     }
// };
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