定义

迭代法又称辗转法，是一种不断用变量的旧值递推新值的过程。

代码示例


public class Iteration {

    /**
     * 斐波那契数列如下
     * 1,1,2,3,5,8,13,21,34....
     * <p>
     * 规律为从第3位开始，每一位数字都是上两位数字之和
     */

    public static long fib(int n) {

        long pre = 1l;
        long current = 1l;
        long next;

        if (n == 1 || n == 2) {

            return 1;
        } else {

            for (int i = 3; i <= n; i++) {

                next = current;
                current = current + pre;
                pre = next;
            }
        }

        return current;
    }

    public static void main(String[] args) {

        System.out.println(fib(1));
        System.out.println(fib(2));
        System.out.println(fib(3));
        System.out.println(fib(4));
        System.out.println(fib(5));


    }
}