Project ForgeData Structures
Trees
GATE 2007
Medium
The maximum number of binary trees that can be formed with three unlabeled nodes is:
- A1
- 5
- C4
- D3
Explanation
The number of distinct (shape-wise) binary trees with n nodes is the nth Catalan number, C_n = (2n choose n)/(n+1). For n=3: C_3 = 5.
Source: GATE CS 2007 (2007)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.