关于一维数组的进一步编程，二维数组

package 一;
import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.*;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.lang.Math;
import java.io.IOException;
import java.math.BigDecimal;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
import java.util.Random;
public class Maxshuzu 
{
    public static void main(String[] args)throws IOException
    {
        File newFile = new File("D:\\Shu.txt");//文本文档的位置
        if(!newFile.exists()) {
            System.out.println("文件无法打开！");
        }
        FileOutputStream out = new FileOutputStream(newFile);
    String[] S=new String[100000];
    BigDecimal[] S1=new BigDecimal[100000];//原串
    BigDecimal[] S2=new BigDecimal[100000];//现有
    System.out.println("请输入您要输入的数目:");
    int a=0;//总数
    Scanner scan=new Scanner(System.in);
    a=scan.nextInt();
    System.out.println("请输入整型数字：");
    for(int i=0;i<a;i++) {
        S[i]=" ";
    }
    for(int i=0;i<a;i++) {
        String s1;
        s1=scan.next();    
        S1[i]=new BigDecimal(s1);
        
    }int l=0;
    for(int i=0;i<a;i++) {
        System.out.println("第"+(i+1)+"个是："+S1[i]);
    }
    for(int i=0;i<a;i++) {
        out.write(String.valueOf(S1[i]).getBytes());
        out.write(String.valueOf(S[i]).getBytes());
    }
    int O=0;
    for(int i=0;i<a;i++) {
        int i1=i+1;
        int o;o=0;
        for(int j=i+1;j<a;j++)
        {    O=O+1;
            BigDecimal m=S1[i]; BigDecimal n=S1[j];
            BigDecimal N=new BigDecimal(0);BigDecimal M=new BigDecimal(0);
            o=o+1;
            if(o==1) {
                M=n.add(m);
                S2[O-1]=M;
            }
            else {
                N=S2[O-2].add(n);
                S2[O-1]=N;
                System.out.println(n);
            }
            l=O;

        }
    }BigDecimal max=BigDecimal.valueOf(0);
    max=S2[0];
    int m0=0;
    int M0=0;
    for(int i=0;i<l-1;i++) {
        BigDecimal m1=BigDecimal.valueOf(0);
        BigDecimal m2=BigDecimal.valueOf(0);
        m1=S2[i];
        m2=S2[i+1];
        int q=2;
        if(max.compareTo(m1)==-1)max=m1;
        if(max.compareTo(m2)==-1)max=m2;
        System.out.println("是否要回滚，回滚-1，不-2");
        q=scan.nextInt();
        for(int i1=0;i1<a;i1++)
        {
            for(int i2=i1+1;i2<a;i2++)
            {
                M0=M0+1;
                System.out.println("第"+M0+"次");
                System.out.println("已经比较了"+M0+"个子数组");
                System.out.println("从第"+(i1+1)+"到第"+(i2+1));
                System.out.println("最大子数组和："+max);
                System.out.println('\n');
                try{Thread.sleep(1000);}catch(Exception e){}
                if(q==1)
                {System.out.println("请输入回退到第几步：");
                M0=scan.nextInt();
                M0=M0-1;
                System.out.println(M0);
                i2=M0;
                }
            }
            
        }

    }
    
    if(max.compareTo(S1[0])==-1) max=S1[0];
    if(max.compareTo(S1[a-1])==-1)max=S1[a-1];
    System.out.println("最大数"+max);
    out.write(String.valueOf("最大数：").getBytes());
    out.write(String.valueOf(max).getBytes());
    out.flush();
    out.close();
    FileReader reader=new FileReader("D:\\Shu.txt");
    BufferedReader br=new BufferedReader(reader);
    String line;
    while((line=br.readLine())!=null) {
        System.out.println(line);
    }
    }
}