Java流程控制练习题

1、输入两个整数，打印两数之差的绝对值。

package com.javawu.demo;

import java.util.Scanner;

public class Demo1 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("输入两个整数，用回车或者空格分隔");
        Scanner scan = new Scanner(System.in);
        int one = scan.nextInt();
        int two = scan.nextInt();
        
        if (one - two >= 0) {
            System.out.println(one - two);
        }else {
            System.out.println(two - one);
        }
    }
}

2、编写一个四则运算器，计算加减乘除，例如输入10 + 20，输出30。

package com.javawu.demo;

import java.util.Scanner;

public class Demo2 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("请输入一个四则运算，用空格分隔");
        
        Scanner scan = new Scanner(System.in);
        int numOne = scan.nextInt();
        String str = scan.next();
        int numTwo = scan.nextInt();
        
        switch(str){
        case "+":
            System.out.println(numOne + numTwo);
            break;
        
        case "-":
            System.out.println(numOne - numTwo);
            break;
            
        case "*":
            System.out.println(numOne * numTwo);
            break;
            
        case "/":
            System.out.println(numOne / numTwo);
            break;
            
            default:
                System.out.println("格式错误");
        }
    }
}

3、输入年月日，计算是一年的第几天，考虑闰年。

package com.javawu.demo;

import java.util.Scanner;

public class Demo3 {
    
    public static void main(String[] args){
        
        System.out.println("请输入年月日，用空格分隔");
        
        Scanner scan = new Scanner(System.in);
        int year = scan.nextInt();
        int month = scan.nextInt();
        int day = scan.nextInt();
        int total = 0;
         
        for (int i = 1; i < month; i++) {
            switch (i) {
            case 1:
                total += 31;
                break;
            case 2:
                if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
                    total += 29;
                } else {
                    total += 28;
                }
                break;
            case 3:
                total += 31;
                break;
            case 4:
                total += 30;
                break;
            case 5:
                total += 31;
                break;
            case 6:
                total += 30;
                break;
            case 7:
                total += 31;
                break;
            case 8:
                total += 31;
                break;
            case 9:
                total += 30;
                break;
            case 10:
                total += 31;
                break;
            case 11:
                total += 30;
                break;
            case 12:
                total += 31;
                break;
            }
        }
        System.out.println(total+day);
    }
}

4、判断一个三位数是否是水仙花数,如果是,输出YES,如果不是,输出NO。
说明:水仙花就是一个数的每个数字的立方和等于它本身的数,例如153就是一个水仙花数111+555+333=153。

package com.javawu.demo;

import java.util.Scanner;

public class Demo4 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("请输入一个三位数");
        
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        
        int hundreds = num/100;
        int tens = num%100/10;
        int ones = num%10;
        
        if (num == hundreds*hundreds*hundreds + tens*tens*tens + ones*ones*ones) {
            System.out.println("YES");
        }else {
            System.out.println("NO");
        }
    }
}

5、输入一个时间,输出时间的下一秒。例如输入的是10 20 59,表示是10点20分59秒,下一秒就是10点21分0秒。

package com.javawu.demo;

import java.util.Scanner;

public class Demo5 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("请输入时分秒，用空格分隔");
        
        Scanner scan = new Scanner(System.in);
        int hours = scan.nextInt();
        int minutes = scan.nextInt();
        int second = scan.nextInt();
        
        if (hours > 12 || minutes > 60 || second > 60) {
            System.out.println("格式错误");
        }else {
            if (second + 1 == 60) {
                minutes ++;
                second = 0;
            }else {
                second ++;
            }
            
            if (minutes == 60) {
                hours ++;
                minutes = 0;
            }else {
                
            }
            System.out.println(hours + "时" + minutes + "分" + second + "秒");
        }
    }
}

6、输入三个整数，x,y,z,把这三个数由小到大输出。

package com.javawu.demo;

import java.util.Scanner;

public class Demo6 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("请输入三个整数，用空格隔开");
        
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        int b = scan.nextInt();
        int c = scan.nextInt();
        
        if (a > b) {
            a = a + b;
            b = a - b;
            a = a - b;
        }
        if (b > c) {
            b = b + c;
            c = b - c;
            b = b - c;
        }
        if (a > b) {
            a = a + b;
            b = a - b;
            a = a - b;
        }
        System.out.println(a);
        System.out.println(b);
        System.out.println(c);
    }
}

7、求1! + 2! + 3! +…+ 5!。

package com.javawu.demo;

public class Demo7 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        int num = 0;
        for (int i = 1; i <= 5; i ++) {
            for (int j = 1; j <= i; j ++) {
                num = num + i * j;
            }
        }
        System.out.println(num);
    }
}

8、输入一个整数，计算该数有多少位 ，例如123有3位。

package com.javawu.demo;

import java.util.Scanner;

public class Demo8 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("请输入一个整数");
        
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        
        int a = 1;
        int time = 0;
        while (num/a != 0) {
            a = a * 10;
            time ++;
        }
        System.out.println(time);
    }
}

9、整数逆序输出,例如输入一个整数12345,输出整数54321。

package com.javawu.demo;

import java.util.Scanner;

public class Demo9 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        System.out.println("请输入一个整数");
        
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        
        int a = 1;
        int time = 0;
        while (num/a != 0) {
            a = a * 10;
            time ++;
        }
        
        System.out.println(time);
        
        int result = 0;
        
        for (int i = 0; i <= time; i ++) {
            int b = num / i * 10;
            System.out.println(b);
            result = result + (time - i+1) * b;
        }
        System.out.println(result);
    }
}

10、打印九九乘法表。

package com.javawu.demo;

public class Demo10 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        for (int i = 1; i <= 9; i ++) {
            for (int j = 1; j <= i; j ++) {
                System.out.print(i + "*" + j + "=" + i * j + "\t");
            }
            System.out.println();
        }
    }
}

11、打印图形。

等腰三角形

package com.javawu.demo;

public class Demo11 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        
        System.out.println();
        System.out.println();
        for (int i = 1; i <= 6; i ++) {
            System.out.print(" ");
            System.out.print(" ");
            for (int j = 1; j <= 6 - i; j ++) {
                System.out.print(" ");
            }
            
            for (int k = 1; k <= i *2 -1; k ++) {
                System.out.print("*");
            } 
            System.out.println();
        }
    }
}