更新时间:2021-07-29 23:26:17
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static ulong Fib(int n)
{
double sqrt5 = Math.Sqrt(5);
double p1 = (1 + sqrt5) / 2;
double p2 = -1 * (p1 - 1);
double n1 = Math.Pow(p1, n + 1);
double n2 = Math.Pow(p2, n + 1);
return (ulong)((n1 - n2) / sqrt5);
}