[leetcode]Pow(x, n)

class Solution {public:    double powPositive(double x, int n){        if(n == 0) return 1;        if(n == 1) return x;                double tmp;        if(n%2 == 0){            tmp = powPositive(x, n/2);            return tmp*tmp;        }                tmp = powPositive(x, n/2);                return tmp*tmp*x;    }        double pow(double x, int n) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(n >= 0) return powPositive(x,n);        return 1/powPositive(x,-n);            }};