字节测开｜笔试第二题｜求助

分4种情况，过了70%，也不知道问题出在哪，想看看大家怎么写的

import java.util.Scanner;
public class test2 {
    public static int flag;
    public static String a;
    public static String b;
    public static int i;
    public static int j;
    public static int t;
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        a = input.next();
        b = input.next();
        flag =1;


//step0：第0个就不同：
        if(flag==1&&a.charAt(0)!=b.charAt(0)){


            a=b.charAt(0)+a.substring(1,a.length());


            flag--;
        }




//step1 最后1个就不同：
        if(flag==1&&a.charAt(i)!=b.charAt(j)){
            a=a.substring(0,i)+b.charAt(j);
            flag--;
        }


        int m = beforefind();
        int n = afterfind();


        int res=m*n;


//step2
        if(flag==1&&i>=0&&j>0&&a.charAt(i)!=b.charAt(j)){
            a=a.substring(0,i)+b.charAt(i)+a.substring(i+1,a.length());
            flag--;
        }
        m = beforefind();
        n = afterfind();
        res = Math.max(res,m*n);


//step3


        if(flag==1&&t<Math.min(a.length()-1,b.length()-1)&&a.charAt(t)!=b.charAt(t)){
            a=a.substring(0,t)+b.charAt(t)+a.substring(t+1,a.length());
            flag--;
        }
        m = beforefind();
        n = afterfind();
        res = Math.max(res,m*n);




        System.out.println(res);






    }


    public static int beforefind(){


        int length = Math.min(a.length(),b.length());
        int m=0;


        for(t=0;t<length;t++){
            if(a.charAt(t)==b.charAt(t)){
                m++;
            }else{
                break;
            }
        }
        
        return m;
        
    }


    public static int afterfind(){
        int n=0;
        i =a.length()-1;
        j =b.length()-1;
        
        while (i>=0&&j>=0&&a.charAt(i)==b.charAt(j)){
            n++;
            j--;
            i--;
        }


        return n;
    }


}