我的情况有点不同，我试图用一种力量创造一个面具，但我想无论如何我都要分享我找到的解决方案。

显然，它只适用于2的幂。

Mask1 = 1 << (Exponent - 1);
Mask2 = Mask1 - 1;
return Mask1 + Mask2;

int pow(int const x, unsigned const e) noexcept
{
  return !e ? 1 : 1 == e ? x : (e % 2 ? x : 1) * pow(x * x, e / 2);
  //return !e ? 1 : 1 == e ? x : (((x ^ 1) & -(e % 2)) ^ 1) * pow(x * x, e / 2);
}

是的，它是递归的，但是一个好的优化编译器会优化递归。

如果你想得到一个整数的2的幂，最好使用shift选项:

Pow(2,5)可以替换为1<<5

这样效率更高。

更一般的解决方案考虑负指数

private static int pow(int base, int exponent) {

    int result = 1;
    if (exponent == 0)
        return result; // base case;

    if (exponent < 0)
        return 1 / pow(base, -exponent);
    int temp = pow(base, exponent / 2);
    if (exponent % 2 == 0)
        return temp * temp;
    else
        return (base * temp * temp);
}

O(log N)的解决方案在Swift…

// Time complexity is O(log N)
func power(_ base: Int, _ exp: Int) -> Int { 

    // 1. If the exponent is 1 then return the number (e.g a^1 == a)
    //Time complexity O(1)
    if exp == 1 { 
        return base
    }

    // 2. Calculate the value of the number raised to half of the exponent. This will be used to calculate the final answer by squaring the result (e.g a^2n == (a^n)^2 == a^n * a^n). The idea is that we can do half the amount of work by obtaining a^n and multiplying the result by itself to get a^2n
    //Time complexity O(log N)
    let tempVal = power(base, exp/2) 

    // 3. If the exponent was odd then decompose the result in such a way that it allows you to divide the exponent in two (e.g. a^(2n+1) == a^1 * a^2n == a^1 * a^n * a^n). If the eponent is even then the result must be the base raised to half the exponent squared (e.g. a^2n == a^n * a^n = (a^n)^2).
    //Time complexity O(1)
    return (exp % 2 == 1 ? base : 1) * tempVal * tempVal 

}

下面是Java中的方法

private int ipow(int base, int exp)
{
    int result = 1;
    while (exp != 0)
    {
        if ((exp & 1) == 1)
            result *= base;
        exp >>= 1;
        base *= base;
    }

    return result;
}