Pow(x, n)
这个注意负数的情况, 用二分做.
public class Solution {
public double myPow(double x, int n) {
if(n == 0)
return 1;
if(n == 1)
return x;
boolean neg = false;
if(n < 0){
neg = true;
n = -n;
}
int k = n / 2;
int l = n - k * 2;
double t1 = myPow(x,k);
double t2 = myPow(x,l);
if(neg)
return 1/(t1*t1*t2);
else
return t1*t1*t2;
}
}