斐波那契数列

Posted 2020-08-28 一行代码的事

/**
 *
 * 有一对兔子，从出生后第3个月起每个月都生一对兔子，小兔子长到第三个月后每个月又生一
 * 对兔子，假如兔子都不死，问每个月的兔子总数为多少？
 * 1.程序分析：兔子的规律为数列1,1,2,3,5,8,13,21....
 * 递归方法：缺点性能极差。优点代码量少。
 */
public class Fibonacci1
{
    public int fibo(int i)
    {
        if(i == 1||i==2)
        {
            return 1;
        }
        else
        {
            return fibo(i-1)+fibo(i-2);
        }
    }

    public static void main(String[] args)
    {
        Fibonacci1 fibonacci = new Fibonacci1();
        int fibo = fibonacci.fibo(1);
        int fibo1 = fibonacci.fibo(2);
        int fibo2 = fibonacci.fibo(3);
        int fibo3 = fibonacci.fibo(4);
        int fibo4 = fibonacci.fibo(5);
        int fibo5 = fibonacci.fibo(6);
        System.out.println(fibo);
        System.out.println(fibo1);
        System.out.println(fibo2);
        System.out.println(fibo3);
        System.out.println(fibo4);
        System.out.println(fibo5);
    }

}

import java.util.Scanner;

/**
 * 计算斐波那契数列(Fibonacci)的第n个值
 * Created by Abbot on 2017-01-19 0019 11:17:01.
 *
 */
public class Fibonacci2
{
    public static void main(String[] args)
    {
        int n = new Scanner(System.in).nextInt();
        int n1 = 1;
        int n2 = 1;
        int sum = 0;
        if (n <= 0)
        {
            System.out.println("参数错误");
            return;
        }
        if (n <= 2)
        {
            sum = 1;
        }
        else
        {
            for(int i = 3; i<=n; i++)
            {
                sum = n1+n2;
                n1 = n2;
                n2 = sum;
            }
        }
        System.out.println(sum);
    }
}

/**
 * Created by Abbot on 2017-01-19 0019 11:23:57.
 * 输出Fibonacci数列
 */
public class Fibonacci3
{
    public static void main(String[] args)
    {
        short i = 0,j= 1;
        do
        {
            if(i == 0)
            {
                System.out.print(j+",");
            }
            else
            {
                System.out.print("" + i + "," + j+",");
            }
            i = (short) (i+j);
            j = (short) (i+j);
        }while(i>0);

        System.out.println();

    }
}

/**
 * Created by Abbot on 2017-01-19 0019 11:32:34.
 * 用一位数组保存Fibonacci序列值
 */
public class Fibonacci4
{
    public static void main(String[] args)
    {
        int n = 25, i;
        int fib[] = new int[n];
        fib[0] = 0;
        fib[1] = 1;
        for (i = 2; i < n; i++)
        {
            fib[i] = fib[i-1]+fib[i-2];
        }
        for(i= 1;i<fib.length;i++)
        {
            System.out.print(""+fib[i]+",");
        }

    }
}