algorithms-finding time complexity

Question

Consider a situation where you don’t have function to calculate power (pow( ) function in C)

and

you need to calculate x^n where x can be any number and n is a positive integer. What can

be the best possible time complexity of your power function?

(a) O (n)

(b) O (n log n)

(c) O(log log n)

(d) O (log n)

Answer 1

D. O(log n)

Here's the implementation: http://stackoverflow.com/a/5231118

Comments

Thanks a lot,i got the solution but main issue is in exam,we wont get this much time to think efficiently