<code>power(a, b)</code> with O(log b) (using even/odd halving) is achieved by
- Acheck_circle
if even: power(a<em>a, b/2); if odd: a</em>power(a, b-1)
- B
Use Math.pow
- C
Always a * power(a, b-1)
- D
Recursion always O(b)
Explanation
Fast exponentiation: divide-and-conquer.