class Solution {
public:int countSubstrings(string s) {vector<vector<bool>> dp(s.size(), vector<bool>(s.size(), false));int res = 0;for(int i = s.size() - 1; i >= 0; i--){for(int j = i; j < s.size(); j++){if(i == j || (s[i] == s[j] && (dp[i + 1][j - 1] || j - i <= 1))){res++;dp[i][j] = true;}}}return res;}
};

class Solution {
public:int longestPalindromeSubseq(string s) {int n = s.size();vector<vector<int>> dp(n, vector<int>(n, 0));for(int i = 0; i < n; i++) dp[i][i] = 1;for(int i = n- 1; i >= 0; i--){for(int j = i + 1; j < n; j++){if(s[i] == s[j]) dp[i][j] = dp[i + 1][j - 1] + 2;else dp[i][j] = max(dp[i + 1][j], dp[i][j - 1]);}}return dp[0][n - 1];}
};