<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>

// faster runtime 
int foo = []()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    return 0;
}();

static const auto _ = [](){
    cin.tie(NULL);
    ios_base::sync_with_stdio(false);
    return 0;
}();

class Solution {
public:
    long long num(int n , int length){
        string a = "";
        int mid;
        if(length&1) mid = (length+1)/2;
        else mid = length/2;
        if(n > 9*pow(10,mid-1)) return -1;
        // cout << "mid : " << mid << endl; 

        for(int i=mid ; i>=1 ; i-- ){ 
            if(n==0) a = a + to_string(9);
            else if(i==mid){
                for( int m=1 ; m<=9 ; m++){
                    if( n<= m * pow(10,i - 1) ){
                        a = a + to_string(m);
                        break;
                    }
                }
            }
            else if(i == 1){
                a = a + to_string(n-1);
            }
            else{
                for( int  m=0 ; m<=9 ; m++){
                    if( n<= (m+1) * pow(10,i-1) ){
                        a = a + to_string(m);
                        break;
                    }
                }

            }
            n = n % (int)pow(10,i-1)    ;
            // cout << i << " " << n << " " << a << endl;
        }

        string ans = a;
        if(length&1){
            a.pop_back();
            reverse(a.begin(),a.end());
            ans = ans + a;
        }
        else{
            reverse(a.begin(),a.end());
            ans = ans + a;
        }

        return stoll(ans);
    }
    vector<long long> kthPalindrome(vector<int>& queries, int intLength) {
        vector<long long> ans;
        for(auto x : queries){
            ans.push_back(num(x,intLength));
        }
        return ans;
    }
};
60200