Java第六次作业
练习
1.使用for循环计算1-100的和,除了以3结尾的那些数
package Second; public class S1 { /** * @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) sum += i; } System.out.println(sum); } }
2.使用二重循环输出以下图形
*
***
*****
*******
*****
****
***
**
*
package Second; public class S2 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub for (int i = 1; i <= 4; i++) { for (int j = 1; j <= 4 - i; j++) { System.out.print(" "); } for (int k = 1; k <= 2 * i - 1; k++) { System.out.print("*"); } System.out.println(); } System.out.println(); System.out.println(); System.out.println(); System.out.println(); } }
package Second; public class S3 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub 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。
package Second; import java.util.Scanner; public class S4 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("输入学生的姓名"); String name = input.next(); while (name != "Q") { name = input.next(); if (name.equals("Q")) break; } System.out.println("程序结束"); } }
package Second;
import java.util.Scanner;
public class S5 {
/**
* @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("输入的成绩无效,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)
package Second; public class S6 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub double sum = 0; double j = 0; for (int i = 1; i <= 10; i++) { sum += i; j = 1 / sum + j; } System.out.println(j); } }
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(判断猜的次数,如果1-3次,提示太棒了 如果5-8次 一般般 如果8次以上 太笨了)
package Second; import java.util.Random; import java.util.Scanner; public class Zuo1 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("猜个随机数"); int s = input.nextInt(); Random r = new Random(); int a = r.nextInt(99) + 1; System.out.println(+a); while (a != s) { if (s > a) { System.out.println("大了点"); } if (s < a) { System.out.println("小了点"); } System.out.println("再猜"); s = input.nextInt(); } System.out.println("猜对了"); } }
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)
package Second; import java.util.Scanner; public class Zuo2 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("请输入大于1的数"); int a = input.nextInt(); boolean shizhishu = true; for (int i = 2; i < a - 1; i++) { if (a % i == 0) { shizhishu = false; break; } } if (shizhishu) { System.out.println("是质数"); } else { System.out.println("不是质数"); } } }
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……
package Second; public class Zuo3 { /** * @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 = 2; i < 20; i++) { c = a + b; a = b; b = c; } System.out.println("第20项" + c); } }