小學四則運算

import java.util.Random;import java.util.Scanner;public class test {    public static void main(String[] args) {        int n;        int number;        int count=0;        Scanner in = new Scanner(System.in);                    do {                System.out.PRintln("请问要计算多少道题目？");                number=in.nextInt();                System.out.println("你要进行多少位数的四则运算？");                n = in.nextInt();            } while (n < 1 && number>0);            for(int i=0;i<number;i++){            int x = new Random().nextInt((int) Math.pow(10, n)) + 1;            int y = new Random().nextInt((int) Math.pow(10, n)) + 1;            int o = new Random().nextInt(4);            float z = 0;            float input;            String c = "?";            boolean bigger = x > y ? true : false;// 小学生不会出现负数啊            switch (o) {            case 0:                c = "+";                z = x + y;                break;            case 1:                c = "-";                if (bigger)                    z = x - y;                else                    z = y - x;                break;            case 2:                c = "*";                z = x * y;                break;            case 3:                c = "/";                z = (float) x / y;                break;            default:                System.out.println("error!");            }                if (!bigger && c.equals("-"))                    System.out.print(y + c + x + "=");                else                    System.out.print(x + c + y + "=");                input = in.nextFloat();                if (input == z || (c.equals("/") && Math.abs(input-z)<0.01)){                    System.out.println("算对了！");                    count++;                }                else                     System.out.println("算错了!");        }            System.out.println("一共计算"+number+"题，算对了"+count+"题，算错了"+(number-count)+"题，正确率为"+(float)count/number*100+"%");    }}