s2.cpp

// OJ: https://leetcode.com/problems/super-palindromes/
// Author: github.com/lzl124631x
// Time: O(1)
// Space: O(1)
// Ref: https://leetcode.com/problems/super-palindromes/discuss/170728/no-more-this-type-questions-for-contest!
typedef unsigned long long ULL;
class Solution {
public:
    int superpalindromesInRange(string L, string R) {
        vector<ULL> v{
            1, 4, 9, 121, 484, 10201, 12321, 14641, 40804, 44944, 1002001, 1234321, 4008004, 100020001, 102030201, 104060401, 121242121, 123454321, 125686521, 400080004 ,404090404, 10000200001l, 10221412201l, 12102420121l, 12345654321l, 40000800004l , 1000002000001l, 1002003002001l, 1004006004001l, 1020304030201l, 1022325232201l, 1024348434201l, 1210024200121l, 1212225222121l, 1214428244121l, 1232346432321l, 1234567654321l, 4000008000004l, 4004009004004l, 100000020000001l, 100220141022001l, 102012040210201l, 102234363432201l, 121000242000121l, 121242363242121l, 123212464212321l, 123456787654321l, 400000080000004l, 10000000200000001l, 10002000300020001l, 10004000600040001l, 10020210401202001l, 10022212521222001l, 10024214841242001l, 10201020402010201l, 10203040504030201l, 10205060806050201l, 10221432623412201l, 10223454745432201l, 12100002420000121l, 12102202520220121l, 12104402820440121l, 12122232623222121l, 12124434743442121l, 12321024642012321l, 12323244744232321l, 12343456865434321l, 12345678987654321l, 40000000800000004l, 40004000900040004l
        };
        return upper_bound(v.begin(), v.end(), stoull(R)) - lower_bound(v.begin(), v.end(), stoull(L));
    }
};