**CBSE NET DECEMBER 2011 PAPER II**

The number of nodes in a complete binary tree of height h (with roots at level 0) is equal to

(A) 2^{0}+2^{1}+......+2^{h}

(B) 2^{0}+2^{1}+......+2^{h-1}

(C) 2^{0}+2^{1}+......+2^{h+1}

(D) 2^{1}+......+2^{h+1}

**Ans:-A**

**Explanation:-**

A complete binary tree have 0 or 2 child per parent. So, count the number of nodes in each level, starting with the root, assuming that each level has the maximum number of nodes.

n=1+2+4+....2^{h-1}+2^{h}