/*
	斐波那契数列  递归算法和非递归算法
	f(0) = 0;
	f(1) = 1;
	f(n) = f(n - 1) + f(n - 2);
*/
#include<iostream>
#include<vector>

using namespace std;

// 递归算法
int Fun1(int n)
{
	if(n == 0)
		return 0;
	else if(n == 1)
		return 1;
	else return Fun1(n - 1) + Fun1(n - 2);
}

// 非递归算法
int Fun2(int n)
{
	if(n == 0)
		return 0;
	else if(n == 1)
		return 1;
	else
	{
		int i = 2;
		int temp1;
		int temp2;
		int sum;
		temp1 = 0;
		temp2 = 1;
		while(i <= n)
		{
			sum = temp1 + temp2;
			
			i++;
			temp1 = temp2;
			temp2 = sum;
		}
		return sum;
	}
}



int main()
{
	cout<<Fun1(20)<<endl;
	cout<<Fun2(20)<<endl;
	 return 0;
}