• 暴力方法每次只乘一次base,考虑将exponent化成二进制,base每次平方,来进行结果的增长
public class Solution {
    public double Power(double base, int exponent) {
        double result = 1.0;
        if(exponent < 0) {
            exponent = -exponent;
            base = 1 / base;
        }
        // 二进制缩减
        while(exponent != 0) {
            if(exponent % 2 == 1) {
                result *= base;
            }
            exponent >>= 1;
            base *= base;
        }
        return result;
  }
}