Pow(x, n).txt

Implement pow(x, n).

//递归求解。用分治法在O(lgn)时间内完成。
//分四种情况n = 0; n != 0 && n is even; n > 0 && n is odd; n < 0 and n is odd
double pow(double x, int n)
{
	if(n == 0)
		return 1.0;
	double half = pow(x, n / 2);
	if(n % 2 == 0)
		return half * half;
	else if(n > 0)
		return half * half * x;
	else 
		return half * half / x;
}