最长回文子串

给你一个字符串 s，找到 s 中最长的回文子串。

public class Solution {
    public String longestPalindrome(String s) {
        int len = s.length();
        if (len < 2) {
            return s;
        }
        int maxLen = 1;
        int begin = 0;
        boolean[][] dp = new boolean[len][len];
        for (int i = 0; i < len; i++) {
            dp[i][i] = true;

        }
        char[] charArray = s.toCharArray();

        for (int L = 2; L <= len; L++) {
            for (int i = 0; i < len; i++) {
                int j = L + i - 1;

                if (j >= len) {
                    break;
                }
                if (charArray[i] != charArray[j]) {
                    dp[i][j] = false;

                } else {
                    if (j - i < 3) {
                        dp[i][j] = true;

                    } else {
                        dp[i][j] = dp[i + 1][j - 1];

                    }
                }
                if (dp[i][j] && j - i + 1 > maxLen) {
                    maxLen = j - i + 1;
                    begin = i;
                }
            }
        }
        return s.substring(begin, begin + maxLen);
    }
}