题解 | #密码截取#

import java.util.Scanner;
import java.io.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line = in.nextLine();
        //dp[i][j] 下标ij是否回文串 dp[i][j]=dp[i+1][j-1]
        boolean[][] dp = new boolean[line.length()][line.length()];
        int max = 1;
        for (int j = 0; j < line.length(); j++) {
            for (int i = 0; i <= j; i++) {
                if (line.charAt(i) == line.charAt(j) && (j - i <= 1 || dp[i + 1][j - 1])) {
                    dp[i][j] = true;
                    max = Math.max(j - i + 1, max);
                }

            }
        }
        System.out.print(max);

    }
}