代码随想录：最长回文子序列

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