题解 | #密码截取#

import java.util.; import java.io.;

public class Main{ public static void main(String[] args) { final InputStreamReader reader = new InputStreamReader(System.in); try( BufferedReader br = new BufferedReader(reader)){

         String password = br.readLine();
         char[] chars = password.toCharArray();
         int size = 0;
        for (int i = 1; i < chars.length-1; i++) {
            size = Math.max(Math.max(getMaxSize(chars,i,i,true,false),getMaxSize(chars,i,i+1,true,true)),size);
        }
        System.out.println(size);


    }catch (IOException e){
        System.out.println(e.getMessage());
    }
}

public static int getMaxSize(char[] chars,int i ,int j,boolean isFirts,boolean type){
    //递归出口
        if (i < 0 || j >chars.length-1) return 0;

        if (type){
            if (chars[i] == chars[j] && isFirts)
                return 2+getMaxSize(chars,i-1,j+1,false,true);
        }else {
            if (chars[i] == chars[j] && isFirts)
                return 1+getMaxSize(chars,i-1,i+1,false,false);
        }


        if (chars[i] == chars[j]) return 2+getMaxSize(chars,i-1,j+1,false,type);

        return 0;

}

}