double myPow(double x, int n) {
        if(x==0) return 1.0;
        if(n==1) return x;
        unsigned int t;
        if(n > 0)
        {
            t = (unsigned int)n;
        }
        else 
        {
            t = (unsigned int)(-n);
        }
        for(double i=1.0; ;x *= x)
        {
            if((t&1) != 0)
            {
                i *= x;
            }
            if((t>>=1) == 0)
                return n>0?i:(1.0)/i;
        }
    }