java 算法练习1

输入一个数，计算所有的位数之和

import java.util.Scanner;
public class sum{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum = 0;
        for(int i = n; i >0; i/=10){
            sum += i % 10;
        }
        System.out.println(sum);
    }
}

计算各图形的面积

import java.util.Scanner;
import java.lang.Math;
public class range{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("1. 长方形");
        System.out.println("2. 正方形");
        System.out.println("3. 三角形");
        System.out.println("4. 圆形");
        int n = sc.nextInt();
        switch (n) {
            case 1:
                System.out.println("请输入长");
                int x = sc.nextInt();
                System.out.println("请输入宽");
                int y = sc.nextInt();
                System.out.println("面积是:"+x*y);
                break;
            case 2:
                System.out.println("请输入边长");
                int l = sc.nextInt();
                System.out.println("面积是:"+l*l);
                break;
            case 3:
                System.out.println("请输入底");
                int b = sc.nextInt();
                System.out.println("请输入高");
                int h = sc.nextInt();
                System.out.println("面积是:"+b*h/2);
                break;
            case 4:
                System.out.println("请输入半径");
                int r = sc.nextInt();
                System.out.println("面积是:" +Math.PI*r*r);
                break;
        
            default:
                break;
        }
    }
}

输入年月，输出天数

import java.util.Scanner;
public class month{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入年：");
        int year = sc.nextInt();
        System.out.println("请输入月：");
        int month = sc.nextInt();
        int[] run = {31,29,31,30,31,30,31,31,30,31,30,31};
        int[] pin = {31,28,31,30,31,30,31,31,30,31,30,31};
        if (year % 400 == 0 || ( year % 4 == 0 && year % 100 != 0 )) {
            switch (month) {
                case 1:
                    System.out.println("有"+run[0]+"天");
                    break;
                case 2:
                    System.out.println("有"+run[1]+"天");
                    break;
                case 3:
                    System.out.println("有"+run[2]+"天");
                    break;
                case 4:
                    System.out.println("有"+run[3]+"天");
                    break;
                case 5:
                    System.out.println("有"+run[4]+"天");
                    break;
                case 6:
                    System.out.println("有"+run[5]+"天");
                    break;
                case 7:
                    System.out.println("有"+run[6]+"天");
                    break;
                case 8:
                    System.out.println("有"+run[7]+"天");
                    break;
                case 9:
                    System.out.println("有"+run[8]+"天");
                    break;
                case 10:
                    System.out.println("有"+run[9]+"天");
                    break;
                case 11:
                    System.out.println("有"+run[10]+"天");
                    break;
                case 12:
                    System.out.println("有"+run[11]+"天");
                    break;
            
                default:
                    break;
            }
        }  else{
            switch (month) {
                case 1:
                    System.out.println("有"+pin[0]+"天");
                    break;
                case 2:
                    System.out.println("有"+pin[1]+"天");
                    break;
                case 3:
                    System.out.println("有"+pin[2]+"天");
                    break;
                case 4:
                    System.out.println("有"+pin[3]+"天");
                    break;
                case 5:
                    System.out.println("有"+pin[4]+"天");
                    break;
                case 6:
                    System.out.println("有"+pin[5]+"天");
                    break;
                case 7:
                    System.out.println("有"+pin[6]+"天");
                    break;
                case 8:
                    System.out.println("有"+pin[7]+"天");
                    break;
                case 9:
                    System.out.println("有"+pin[8]+"天");
                    break;
                case 10:
                    System.out.println("有"+pin[9]+"天");
                    break;
                case 11:
                    System.out.println("有"+pin[10]+"天");
                    break;
                case 12:
                    System.out.println("有"+pin[11]+"天");
                    break;
            
                default:
                    break;
            }
        } 
    }
}

本文地址：https://blog.csdn.net/weixin_45773503/article/details/107689846