package jianzhi_offer;public class value_cifang {public static void main(String[] args) {// TODO Auto-generated method stubdouble result = Power(2,-3);System.out.println(result);}public static double Power(double base, int exponent) {//指数为0或者底数为1返回1if(base == 1 || exponent == 0) {return 1;}//求指数的绝对值，之后对指数为负的情况进行处理int exp = exponent;if(exponent < 0) {exp = -exp;}//求幂次方double result = valuePower(base,exp);if(exponent < 1) {result = 1/result;}return result;}public static double valuePower(double base,int exponent) {if(base == 1 || exponent == 0) {return 1;}//指数为1返回底数if(exponent == 1) {return  base;}//递归求一半的值double result = valuePower(base,exponent>>1);//一半的值已经求出来了再平方，如果是奇数还要乘以一次底数result*=result;if(exponent%2!=0) {result*= base;}return result;}}