package math;

public class Fibonacci {
    public static void main(String[] args) {
        int n = 10; // 要生成的斐波那契数列的长度
        System.out.println("Fibonacci Series up to " + n + " terms:");
        for (int i = 0; i < n; i++) {
            System.out.print(fibonacci(i) + " ");
        }
    }


    public static void main2() {
        int n = 10; // 要计算的斐波那契数列的长度
        System.out.println("斐波那契数列前 " + n + " 个数为：");
        for (int i = 0; i < n; i++) {
            System.out.print(fibonacci2(i) + " ");
        }
    }

    /**
     * 斐波那契数列 递归实现
     *
     * @param n
     * @return
     */
    public static int fibonacci(int n) {
        if (n <= 1) {
            return n;
        } else {
            return fibonacci(n - 1) + fibonacci(n - 2);
        }
    }

    /**
     * 迭代法实现斐波那契数列
     *
     * @param n
     * @return
     */
    public static int fibonacci2(int n) {
        if (n <= 1) {
            return n;
        }
        int fib = 0;
        int prev1 = 0;
        int prev2 = 1;
        for (int i = 2; i <= n; i++) {
            fib = prev1 + prev2;
            prev1 = prev2;
            prev2 = fib;
        }
        return fib;
    }
}