50.Pow(x, n)
class Solution {
public:
double myPow(double x, int n) {
double res = 1.0;
for (int i = n; i != 0; i /= 2) {
if (i % 2 != 0) res *= x;
x *= x;
}
return n < 0 ? 1 / res : res;
}
};
class Solution {
public double myPow(double x, int n) {
if (n < 0)
return 1/pow(x,-n);
return pow(x,n);
}
private double pow(double x, int n) {
if (n == 0)
return 1;
double res = pow(x, n/2);
if (n%2 == 0)
return res * res;
return x * res * res;
}
}