Java代码实现：Fibonacci斐波那契数列实现使用递归和非递归方法

贤不遗野，天下一家，无名无德，光耀中华。——《诸葛亮》 

//1,3,6,10,15
public class TriangleNumber {

	public static void main(String[] args) {
		TriangleNumber tn = new TriangleNumber();
		
		System.out.println(tn.recursiondemo(2020));
		System.out.println(tn.demo(2020));
	}

	public int demo(int n) {//非递归
		int tatal = 0;
		while (n > 0) {
			tatal += n;
			n--;
		}
		return tatal;
	}

	public int recursiondemo(int n) {
		if (n == 1) {
			return 1;
		} else {
			return n + recursiondemo(n - 1);
		}
	}
}