弟弟的作业 （Java代码）

参考代码:

import java.util.*;

public class Main {

    public static void main(String[] args) {

        int count=0;

        Scanner sc=new Scanner(System.in);

        while(sc.hasNext())            //读取到以文件结尾

        {

            String str1=sc.next();

            int opIndex;                     //读取'+'、'-'、' ='的下标，从而得到a b c的字符串

            if(str1.indexOf('+')!=-1)

                opIndex=str1.indexOf('+');

            else

                opIndex=str1.indexOf('-');

            int eqIndex=str1.indexOf('=');

            String astr=str1.substring(0,opIndex);           //将记录a b c的字符串转换成int

            String bstr=str1.substring(opIndex+1,eqIndex);

            String cstr=str1.substring(eqIndex+1);

            int a=Integer.parseInt(astr);

            int b=Integer.parseInt(bstr);

            int c;

            if(str1.charAt(eqIndex+1)!='?')

                c=Integer.parseInt(cstr);

            else

                continue;

            char op=str1.charAt(opIndex);

            if(op=='+'&&c==a+b)

                count++;

            if(op=='-'&&c==a-b)

                count++;

        }

        System.out.println(count);

    }

}