f(n) = f(n - 1) + f(n-2) + ...+ f(1)
f(n - 1) = f(n -2) + f(n-3) + ...+ f(1)
两式相减 f(n) = 2f(n -1)
class Solution { public: int jumpFloorII(int number) { int n = 1; for(int i = 2; i <= number; i++){ n = 2 * n; } return n; } };
原文：https://www.cnblogs.com/hi3254014978/p/12465412.html