1.使用for循环计算1-100的和,除了以3结尾的那些数
public class lwm1 { /** * @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); } }
2.使用二重循环输出以下图形
*
***
*****
*******
public class lwm2 { /** * @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 a = 1; a <= 2 * i - 1; a++) { System.out.print("*"); } System.out.println(); } } }
*****
****
***
**
*
public class lwm3 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub for (int i = 5; i >= 1; i--) { for (int j = 1; j <= i; j++) { System.out.print("*"); } System.out.println("\t"); } } }
3.循环输入学生姓名,直到输入‘Q’程序结束。
import java.util.Scanner; public class lwm4 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("请输入学生姓名"); String name = input.next(); while (true) { 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 lwm5 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("输入五个学生成绩"); int sum = 0, i = 1; while (i < 6) { int a = input.nextInt(); if (a < 0 || a > 100) { System.out.println("请重新输入"); } else { sum += a; i++; } } System.out.println("五个学生成绩总和为" + sum); } }
5.计算 1+1/(1+2) + 1/(1+2+3) +1/(1+2+3+4)+…………+1/(1+2+....+10)
public class lwm6 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub double sum = 0; double a = 0; for (int i = 1; i < 11; i++) { a += i; sum += 1 / a; } 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”直到猜对为止。
(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)
import java.util.Random; import java.util.Scanner; public class lwm1 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); Random r = new Random(); int a = r.nextInt(100); System.out.println("随机的数为" + a); int b = 0; while (b <= 8) { System.out.println("请输入数字"); int c = input.nextInt(); if (c > a) { System.out.println("大了点"); b++; System.out.println("输入次数为" + b); } else if (c < a) { System.out.println("小了点"); b++; System.out.println("输入次数为" + b); } else { b++; System.out.println("输入次数为" + b); System.out.println("输入正确"); if (b <= 3) { System.out.println("输入次数为" + b); System.out.println("太棒了"); } else if ((b > 3) && (b < 9)) { System.out.println("一般般"); } else { System.out.println("太笨了"); } b++; 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 lwm2 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("输入一个数"); int a = input.nextInt(); if (a%2==0||a/10>0&&a%3==0||a%4==0||a/10>0&&a%5==0||a%6==0||a/10>0&&a%7==0||a%8==0||a%9==0) { System.out.println("不是质数"); } else { System.out.println("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……
public class lwm3 { /** * @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(b); } }