Java第六周上机练习+作业

上机练习

1.使用for循环计算1-100的和，除了以3结尾的那些数

public class Text1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int sum = 0;
        for (int i = 1; i <= 100; i++) {
            if (i % 10 != 3 && i != 3)
                sum += i;
        }
        System.out.println("sum=" + sum);

    }

}

 

 

2.使用二重循环输出以下图形

*
***
*****
*******

*****
****
***
**
*

public class Text2 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 4; i++) {
            for (int x = 1; x <= 4 - i; x++) {
                System.out.print(" ");
            }

            for (int j = 1; j <= 2 * i - 1; j++) {
                System.out.print("*");
            }
            System.out.println();

        }
        System.out.println();
        System.out.println();
        System.out.println();
        System.out.println();
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= 6 - i; j++) {
                System.out.print("*");
            }
            System.out.println();
        }

    }

}

 

 3.循环输入学生姓名，直到输入‘Q’程序结束。

import java.util.Scanner;

public class Text3 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);

        for (;;) {
            System.out.println("输入学生姓名");
            String name = input.next();
            if (name.equals("Q"))
                System.out.println("程序结束");
            break;

        }

    }

}

 

 4.输入5个学生成绩，求和，当输入不合法的时候，提示输入错误重新输入。

import java.util.Scanner;

public class Text4 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("输入学生成绩");
        int sum = 0;
        for (int i = 1; i <= 5; i++) {
            int grade = input.nextInt();
            while (grade < 0 || grade > 100) {
                System.out.println("输入错误请重新输入");
                grade = input.nextInt();
                break;
            }
            sum += grade;
        }
        System.out.println(sum);

    }

}

5.计算 1+ 1/(1+2)+  1/(1+2+3)+  1/(1+2+3+4) +…………+1/(1+2+....+10)

 

public class Text5 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        double sum=0;
        for(int i=1;i<=10;i++){
            sum=sum+1/(sum+i);
        }
        System.out.println(sum);

    }

}

 

 

 作业

1.产生一个1-99的随机数，猜数字，若大了就提示“大了点”，若小了就提示“小了点”直到猜对位置

import java.util.Random;
import java.util.Scanner;
 
public class Homework1 {
 
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Random r = new Random();
        int x = 1 + r.nextInt(98);
        Scanner input = new Scanner(System.in);
        System.out.println("请输入1~99的随机数");
        int s = input.nextInt();
        int a = 1;
        while (a >= 1) {
            if (s > x) {
 
                System.out.println("大了点");
                int j = input.nextInt();
                s = j;
                a++;
            } else if (s < x) {
                System.out.println("小了点");
                int j = input.nextInt();
                s = j;
                a++;
            } else {
                a++;
                if (a <= 3)
                    System.out.println("太棒了");
                if (a >= 4 || a <= 8)
                    System.out.println("一般般");
                if (a > 8)
                    System.out.println("太笨了");
                break;
            }
        }
 
    }
 
}

 

 2.输入一个数，判断是不是质数（只能被1和自身整除的数是质数）

import java.util.Scanner;

public class Homework2 {
     public static void main(String[] args){
         Scanner input=new Scanner(System.in);
            System.out.println("请输入一个数：");
            int num=input.nextInt();
            int a=0, i=2;
            while(i<num)
            {
                if(num%i==0)
                {
                    System.out.println(num+"不是质数");
                    a++;
                    break;
                }
                    i++;
            }
            if(a==0)
            {
                System.out.println(num+"是质数");
            }
      }

}

 

 

3.求裴波那契数列的第20项是什么。裴波那契数列，1,1,2,3,5,8,13，21……

import java.util.Scanner;

public class Homework3 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a=1;
        int b=1;
        int c=0;
        for(int i=1;i<=18;i++){
            c=a+b;
            a=b;
            b=c;
        }
            System.out.println("第20项为"+c);
    }
}