//非遞迴
int main()
{
	int a = 0;
	int b = 1;
	int c = 0;
	int i = 0;
	int n = 0;
	printf("請輸入數字n(n>2)求第n個斐波那契數：");
	scanf("%d",&n);
	for(i = 0;i<n-2;i++)//第一第二個為0,1
	{
		c = a + b;
		a = b;
		b = c;

	}
	printf("%d",b);
	return 0;

}

//遞迴
int fib(int n)
{
	if(n<=2)
		return 1;
	else
		return fib(n-1)+fib(n-2);

}
//用遞迴指數增長，效率太低，
//迭代
int fib(int n)
{
	int a = 1;
	int b = 1;
	int c = 0;
	int i = 0;
	if(n<=2)
		return 1;
	else
	{
		for(i = 0;i<n-2;i++)
		{
			c = a+b;
			a = b;
			b = c;
		}
	}
	return c;

}

int main()
{
	int n = 0;
	int ret = 0;
	printf("請輸入數字n：");
	scanf("%d",&n);
	fib(n);
	ret = fib(n);
	printf("%d",ret);
	return 0;

}