Sword refers to the integer power of Offer-15 value

public static double myPow(double x, int n) {
    if (x == 0){
        return 0;
    }
    // Execute when n = -2147483648
    // n = -n will cause an assignment error due to out of bounds
    // The solution is to first store n into the long variable l and then use l to operate
    long l = n;
    double res = 1;
    // If the exponent is negative, set x to the reciprocal and the exponent becomes positive for looping
    if(l < 0) {
        x = 1 / x;
        l = -l;
    }
    // When n is even: x^n = (x^2)^{n//2}
    // When n is odd: x^n = x(x^2)^{n//2}
    while(l != 0) {
        if((l & 1) == 1){
            res *= x;
        }
        x *= x;
        l >>= 1;
    }
    return res;
}

 

The idea in the while loop gives a picture for easy understanding