16. 数值的整数次方

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class Solution
{
public:
    // double myPow(double x, int n)
    double myPow(double base, int exp)
    {
        if(base == 1 || exp == 0) return 1;

        base = (exp > 0 ? base : 1 / base);
        long positiveExp = abs((long)exp);

        double result = 1;
        while(positiveExp > 0)
        {
            if(positiveExp & 1) result *= base;

            base *= base;
            positiveExp >>= 1;
        }

        return result;
    }
};