public class Fibonacci {

	public static long F(int N){
		int f0 = 0;
		int f1 = 1;
		int fn = 0;
		if(N == 0) return f0;
		if(N == 1) return f1;
		for(int i = 1; i < N; i++){
			fn = f0 + f1;
			f0 = f1;
			f1 = fn;
		}
		return fn;
	}
	
	public static long RecursionF(int N){
		if(N == 0) return 0;
		if(N == 1) return 1;
		return RecursionF(N - 1) + RecursionF(N - 2);
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int N = 4;
		System.out.println(F(N));
		System.out.println(RecursionF(N));
	}

}
 

當要求的數值變大時，遞迴的方法就會顯得很慢，沒有迴圈那麼快速。