《编程之美》学而思 - 斐波那契数列（Fibonacci sequence）

int FibonacciRecursion(int n)//递归
{

if (n > 2)
return (FibonacciRecursion(n - 1) + FibonacciRecursion(n - 2));
else if (n==2)
return 1;
else if (n == 1)
return 0;

return 1;
}

int FibonacciRecurrence(int n)//递推
{
if (n == 2)
return 1;
else if (n == 1)
return 0;

int p1 = 0;
int p2 = 1;
int result = 0;
for (int i = 3; i <= n; i++)
{
result = p1 + p2;
p1 = p2;
p2 = result;
}

return result;
}

const double r1 = 1.61803398874989484820458683436565;
const double r2 = -0.61803398874989484820458683436565;
const double s = 2.23606797749979;  //std::sqrt(5.0);
double FibonacciGoldenRatio(int n)//黄金分割
{
return ((std::pow(r1, n) - std::pow(r2, n)) / s);
}