516.最长回文子序列

class Solution {
public:
    int longestPalindromeSubseq(string s) {
        // dp[i][j]：字符串s在[i, j]范围内最长的回文子序列的长度为dp[i][j]
        vector<vector<int>>dp(s.size(),vector<int>(s.size(),0));
        for (int i = 0; i < s.size(); i++) dp[i][i] = 1;
        for (int i = s.size() - 1; i >= 0; i--) {
            for (int j = i + 1; j < s.size(); 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][s.size() - 1];
    }
};