[数据结构与算法]Java 快乐练习口算

import java.util.Random;
import java.util.Scanner;

public class RandNum2 {

    public static int ProduceNum(int range){
        Random random = new Random();
        int b1 = random.nextBoolean() ? 1 : -1;
        int b2 = random.nextBoolean() ? 1 : -1;
        int b3 = random.nextBoolean() ? 1 : -1;
        int a = random.nextInt(range) * b1;
        int b = random.nextInt(range) * b2;
        int c = random.nextInt(range) * b3;

        System.out.print(a);
        System.out.print(" " + b + " ");
        System.out.println(c);

        return a + b + c;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int rang;
        int questionNum;
        int errCount = 0;

        System.out.println("输入您想做多少题：");
        questionNum = scanner.nextInt();
        System.out.println("输入最大的数：");
        rang = scanner.nextInt();

        System.out.println("\n开始喽。。");

        long startTime = System.currentTimeMillis();
        for (int i = 0; i < questionNum; i++) {
            int randNum = ProduceNum(rang);
            int scana = scanner.nextInt();

            if (scana == randNum){
                System.out.println("good" + '\n');
            }
            else {
                System.out.println("errCount++" + '\n');
                errCount += 1;
            }
        }
        long endTime = System.currentTimeMillis();
        long timeSecondsSpend = (endTime - startTime)/1000;

        System.out.println("错误率：" + (double)errCount/questionNum * 100 + "%");
        System.out.println("耗时：" + timeSecondsSpend + "s");
        System.out.println("平均耗时：" + timeSecondsSpend / questionNum + "s/题");
    }
}

运行实例：

。。。
错误率：10.0%
耗时：34s
平均耗时：3s/题