Java中的斐波那契数、水仙花、顺序输出等例题（简单明了）

目录

1、斐波那契数

2、水仙花数

3、顺序输出

4、阶层的和

5、乘法表

1、斐波那契数

使用递归方法来实现

import java.util.Scanner;

public class Recursion {
    public static int fib(int n) {
        if(n == 1 || n == 2){
            return 1;
        }else{
            return fib(n-1) + fib(n-2);
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        System.out.println(fib(n));
    }
}

使用循环迭代方法，这个更快的实现

import java.util.Scanner;

public class Recursion { 
   public static int fib2(int n) {
        if(n == 1 || n == 2) {
            return 1;
        }else {
            int f1=1;
            int f2=1;
            int f3=0;
            for (int i = 3; i <= n; i++) {
                f3 = f1 + f2;
                f1 = f2;
                f2 = f3;
            }
            return f3;
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        System.out.println(fib2(n));
    }
}

2、水仙花数

public class Main {
    public static void main(String[] args) {
        for (int i = 0; i < 1000; i++) {
            int a = i/100;
            int b = i/10%10;
            int c = i%10;
            if(i == a*a*a+b*b*b+c*c*c) {
                System.out.println(i+"是水仙花数");
            }
        }
    }

}

3、顺序输出

import java.util.Scanner;

public class Main {
    public static void everOne(int n) {
        if(n < 9){
            System.out.print(n+" ");;
        }else{
            everOne(n/10);
            System.out.print(n%10+" ");
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        everOne(n);
    }
}

4、阶层的和

import java.util.Scanner;

public class Main {
    public static int facSum(int n) {
        int sum = 0;
        for (int i = 1; i <= n; i++) {
            sum = sum + fac(i);
        }
        return sum;
    }
    public static int fac(int n) {
        if(n == 1){
            return 1;
        }else {
          return n*fac(n - 1);
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int tmp = fac(n);
        int sum = facSum(n);
        System.out.println(sum);
    }

}

5、乘法表

import java.util.Scanner;

public class main {
    public static void timesTable(int n) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(i+"*"+j+"="+i*j+" ");

            }
            System.out.println();
        }

    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        timesTable(n);
    }
}