leetcode-50-pow(x, n)

public double (double x, int n) {
    if(n > 0 && n <= 10) {
        double t = x;
        while(n > 1) {
            t *= x;
            n--;
        }
        return  t;
    }
    if(n < 0 && n >= -10) {
        x = 1/x;
        double t = x;
        while(n < -1) {
            t *= x;
            n++;
        }
        return t;
    }
    if(n == 0) {
        return 1;
    }
    double haft = myPow(x, n >> 1);
    double haft2 = haft * haft;
    if((n & 1)== 1) {
        return haft2 * x;
    } else {
        return haft2;
    }
}