906

class Solution {
public:
    int superpalindromesInRange(string left, string right) {
        long long LIMIT = int(sqrt(1e9)), L = stoll(left), R = stoll(right), ans = 0;

        // Even length number
        for(int i=1; i<LIMIT; i++){
            string pre = to_string(i);
            string suf = pre;
            reverse(suf.begin(), suf.end());
            string num = pre + suf;
            long long number = stoll(num);
            if(number >= 1e9) break;
            long long square = number*number;
            if(square > R) break;
            if(square >=L && square <= R)
                if(isPalindrome(square)) ans++;
        }

        // Odd length number
        for(int i=1; i<LIMIT; i++){
            string pre = to_string(i);
            string suf = pre.substr(0, pre.length()-1);
            reverse(suf.begin(), suf.end());
            string num = pre+suf;
            long long number = stoll(num);
            if(number >= 1e9) break;
            long long square = number*number;
            if(square > R) break;
            if(square >=L && square <= R)
                if(isPalindrome(square)) ans++;
        }
        return ans;
    }

    bool isPalindrome(long long num){
        long long tmp = num, reverse=0;
        while(tmp){
            reverse *= 10;
            reverse += tmp%10;
            tmp /= 10;
        }
        return reverse ==  num;
    }

};