题解 | #最长回文子串#

import java.util.*;

public class Main{

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    String str = in.nextLine();
    //len:每次外层循环截取的子串固定长度（以该固定长度移动）,从最大开始递减
    for(int len = str.length(); len >=1; len-- ){
        //以固定长度滑动截取
        for(int i = 0; i+len <= str.length(); i++){
            String subStr = str.substring(i, i+len);
            if(isSpecialStr(subStr)){
                System.out.println(subStr.length());
                return;
            }
        }
    }
}

//判断是否是回文串，即前后对称
private static boolean isSpecialStr(String subStr) {
    char[] chars = subStr.toCharArray();
    for(int i = 0, j = chars.length-1; i < chars.length / 2; i++, j--){
        if(chars[i] != chars[j]){
            return false;
        }
    }
    return true;
}

}