每日AC

#include <iostream>
#include <vector>
#include <string>

using namespace std;

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 l = 2; l <= n; l++) {
    for (int i = 0; i <= n - l; i++) {
        int j = i + l - 1;
        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];

}

int main() {

string s;
cin >> s;
cout << longestPalindromeSubseq(s) << endl;
return 0;

}