剑指OFFER----面试题16. 数值的整数次方

链接：https://leetcode-cn.com/problems/shu-zhi-de-zheng-shu-ci-fang-lcof/

代码：

class Solution {
public:
    double myPow(double x, int n) {
        if(n == 0) return 1.0;
        double res = 1;
        long long t = n > 0 ? n: -(long long)n;
        while(t){
            if(t & 1) res = res*x;
            x *= x;
            t >>= 1;
        }
        if(n < 0) res = 1/res;
        return res;
    }
};