一维数组4.25

实现对运算的控制

package shuzu5;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
 
public class shuzu5 {
    static Scanner cin = new Scanner(System.in);    
    public static void readFileByLines(String fileName) {
        File file = new File(fileName);
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader(file));
            String tempString = null;           
//            while ((tempString = reader.readLine()) != null) {
//                System.out.println(tempString);                
//            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }
    
    public static long[] toArrayByFileReader1(String name) {
        // 使用ArrayList来存储每行读取到的字符串
        ArrayList<String> arrayList = new ArrayList<>();
        try {
            FileReader fr = new FileReader(name);
            BufferedReader bf = new BufferedReader(fr);
            String str;
            // 按行读取字符串
            while ((str = bf.readLine()) != null) {
                arrayList.add(str);
            }
            bf.close();
            fr.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 对ArrayList中存储的字符串进行处理
        int length = arrayList.size();
        long[] array = new long[length];
        for (int i = 0; i < length; i++) {
            String s = arrayList.get(i);
            array[i] = Long.parseLong(s);
        }
        long[] newarray = new long[5*length];//剪开带子后新数组
        long[] result = new long[1000];//存放求和子数组
        int rs=0;//子数组计数器
        ArrayList<bean> blist = new ArrayList<bean>();
//        for(int j = 0;j < array.length;j++)
//        {              
//                newarray[k++] = array[j];
//                newarray[j+array.length] = array[j];
//        } 
        int mlist,slist=0;
        long max;
        int i=0;
        int start=0;
        int end=0;
        String choice="y";
        while(choice.equals("y")&&i<length)        //O（n^2）求子数组之和
        {
            mlist = 0;
            int j = i;
            while(choice.equals("y")&&j<length)
            {
                mlist +=array[j];
                result[rs++] = mlist;        //将子数组之和存在数组result[]内
                System.out.println("第"+ (slist+1) +"个子数组的和为：" + mlist);
                slist++;
                max = result[0];                            //将子数组和数组第一个值给max，然后循环进行比较，求出最大值
                for(int kas = 0;kas<slist;kas++)
                {
                    if(max < result[kas])
                        {max = result[kas];end=kas;start=i;}//i有问题
                }
                j++;
                //将新数组存一下
                bean bean=new bean(slist,mlist,max,start,end);
                blist.add(bean);
                System.out.println("当前数组的子数组之和的最大值为："+max);
                System.out.println("最大值从第"+(start+1)+"到第"+(end+1)+"位");
                System.out.println("是否继续，继续则输入y;如果回退，输入b");
                choice=cin.nextLine();
                if(choice.equals("b")) {
                    System.out.println("回退到第几位？");
                    int nr = cin.nextInt();
                    if(nr>blist.size())
                        {
                        System.out.println("输入有误！");
                        }
                    else {
                    System.out.println("第"+ (blist.get((nr-1)).n) +"个子数组的和为：" + blist.get((nr-1)).sum);
                    System.out.println("当前数组的子数组之和的最大值为："+blist.get((nr-1)).max);
                    System.out.println("最大值从第"+(blist.get((nr-1)).start+1)+"到第"+(blist.get((nr-1)).end+1)+"位");
                    
                    }
                }
            }
            i++;            
        }
        max = result[0];                            //将子数组和数组第一个值给max，然后循环进行比较，求出最大值
        for(int h = 0;h<slist;h++)
        {
            if(max < result[h])
                max = result[h];
        }
        //将新数组存一下        
        System.out.println("该数组的子数组之和的最大值为："+max);      
        // 返回数组
        return array;
    }   


    public static void main(String[] args) throws IOException{      
        String name = new String("E:\\Program Files\\eclipse操作\\shuzu\\src\\test2\\input.txt");       
        readFileByLines(name);
        toArrayByFileReader1(name);//文件路径       
    }
}

 

 

只是没有实现会退后循环，目前是回退之后便结束，还有待提升