单选题：When solving a problem with input size $$N$$ by divide and conqu

When solving a problem with input size $$N$$ by divide and conquer, if at each step, the problem is divided into 4 sub-problems of size $$\sqrt N$$, and they are conquered in $$O(logN)$$. Which one of the following is the closest to the overall time complexity $$T(N)$$? Suppose that $$T(2) = O(1)$$ and all related root values are integers. @[B](3)

A. $$O(logN)$$
B. $$O(log^2N)$$
C. $$O(N)$$
D. $$O(loglogN)$$




A.$$O(logN)$$
B.$$O(log^2N)$$
C.$$O(N)$$
D.$$O(loglogN)$$


答案：B