Binary search works, compute the value and multiply it by -1 if the input was negative.

Newton's method is the best.

1. binary search 2. Newton's method

There is only one technical question Half of the time was spent on my past experience

got rejection just because this reason? How was your performance in other 2 questions?

Time Complexity of optimized solution: O(logn) Let us extend the pow function to work for negative y and float x. /* Extended version of power function that can work for float x and negative y*/ #include float power(float x, int y) { float temp; if( y == 0) return 1; temp = power(x, y/2); if (y%2 == 0) return temp*temp; else { if(y > 0) return x*temp*temp; else return (temp*temp)/x; } } /* Program to test function power */ int main() { float x = 2; int y = -3; printf("%f", power(x, y)); getchar(); return 0; }