题解 | #最长回文子串#

非栈，复杂

import java.util.*;

public class Main{
    public static void main(String[]args){
        Scanner input = new Scanner(System.in);
        while(input.hasNextLine()){
            String a = input.nextLine();
            int sum = 0;
            int alre=0;
            if(isHuiWen(a)!=0){
                sum = isHuiWen(a);
                System.out.println(sum);
                alre = 1;
            }
            
            
            for(int j = 0; j<a.length();j++){
                for(int i = 0; i<a.length()-j;i++){
                    if(isHuiWen(a.substring(j,a.length()-1-i)) > sum){
                        sum = isHuiWen(a.substring(j,a.length()-1-i));
                        }
                    }
                }

            if(sum <= 1){
                sum = 1;
            }
            if(alre == 0){
                System.out.println(sum);
            }
            
        }
    }
    public static int isHuiWen(String a){
        int flag = a.length();
        if(flag % 2 == 0){ //双数长度
            for(int i = 0; i < a.length()/2; i++){
                if(a.charAt(i)!=a.charAt(a.length()-i-1)){
                    flag = 0;
                    return flag;
                }
            }
        }
        else{ //单数长度
            for(int i = 0; i < a.length()/2; i++){ //这个长度可能不是int，出错了直接floor
                if(a.charAt(i)!=a.charAt(a.length()-i-1)){
                    flag = 0;
                    return flag;
                }
            }
        }
        
        return flag;
    }
    
}