题目:

给定一个double类型的浮点数base和int类型的整数exponent。求base的exponent次方。

public double Power(double base, int exponent) {
      if (exponent == 0) {
          return 1;
      }
      if (exponent < 0) {
          return 1 / Power(base, -exponent);

      }
      if (exponent > 0) {
          double sum = 1;
          for (int i = 0; i < exponent; i++) {
              sum = base * sum;
          }
          return sum;
      }
      return 0;
  }