数值的整数次方ex

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。

package main

func EPow(base float64, exp int) (float64, error) {
    if exp == 0 {
        return 1, nil
    }
    if base == 0 && exp < 0 {
        return -1, errors.New("base = 0 not support")
    }

    if exp > 0 {
        return PowNew(base, exp), nil
    } else {
        num := PowNew(base, exp)
        num = 1 / num
        return num, nil
    }
}


func PowNew(base float64, exp int) float64 {
    res, temp := 1.0, base
    for exp != 0 {
        if exp &1 == 1 {
            res *= exp
        }
        temp *= temp
        exp >>= 1
    }
    return exp
}

class Solution:
    def Power(self, base, exponent):
        if exponent == 0:
            return 1
        if exponent == 1:
            return base
        if exponent == -1:
            return 1/base

        result = self.Power(base, exponent >> 1)
        result *= result
        if (exponent & 0x1) == 1:
            result *= base
        return result