代码随想录算法训练营day57 647.回文子串 516.最长回文子序列

题目链接647.回文子串

class Solution {
    public int countSubstrings(String s) {
        int len = s.length();
        boolean[][] dp = new boolean[len][len];
        int res = 0;
        for(int i = len - 1; i >=0; i--){
            for(int j =i; j < len; j++){
                if(s.charAt(i) == s.charAt(j)){
                    if(j - i <= 1){
                        dp[i][j] = true;
                        res++;
                    }else if(dp[i+1][j-1]){
                        dp[i][j] = true;
                        res++;
                    }
                }
            }
        }
        return res;
    }
}

题目链接516.最长回文子序列

class Solution {
    public int longestPalindromeSubseq(String s) {
        int len = s.length();
        int[][] dp = new int[len][len];
        for(int i = len - 1; i >= 0; i--){
            dp[i][i] = 1;
            for(int j = i + 1; j