算法 二分求幂(快速取幂)

// 非递归double mypow(double base,int r){double res=1.0;while(r){if((r&1)==1)res*=base;base*=base;r=r>>1;}return res;}// 递归double mypow(double base,int r){if(r==0)return 1.0;if(r==1)return base;double res=mypow(base,r>>1);res*=res;if((r&1)==1)res*=base;return res;}