c_cpp 50. Pow（x，n）

Posted 2021-05-14

class Solution {
public:
    double myPow(double x, int n) {
    	double ans = 1;
    	unsigned long long p;
    	if (n < 0) {
    		p = -n;
    		x = 1 / x;
    	} 
        else
    		p = n;
        
		while (p) {
			if (p & 1)
				ans *= x;
			x *= x;
			p >>= 1;
		}
		return ans;
    }
};