class Solution { public: double f(double x,int y) { double base=x, r=1; while(y) { if(y&1) r=r*base; base=base*base; y>>=1; } return r; } double Power(double base, int exponent) { if(exponent<0){ base=1/base; exponent=-exponent; } return f(base,exponent); } };
快速幂模板题。