递归与非递归求阶乘

递归求5!：

public class Test {

    public int digui(int n) {
        if (n > 1)
            return n * (digui(n - 1));
        else
            return 1;
    }

    public static void main(String[] args) {
        Test test = new Test();
        System.out.println(test.digui(5));  //result=120
    }
}

当n>1时，a=n(n-1)n(-2)2 当n=1时，结果为a1。

非递归求5!

public class Test {

    public int nodigui(int n) {
        int s = 1;
        while (n > 1) {
            s *= n;
            n--;
        }
        return s;
    }

    public static void main(String[] args) {
        Test test = new Test();
        System.out.println(test.nodigui(4));
    }
}