Data Structures · Question 14 · Hard
How many structurally different binary trees can be formed with exactly 3 nodes?
- 5
- 3
- 6
- 4
Answer and explanation
Answer: A. 5
Explanation: The count is the Catalan number C(3) = 6! / (4! × 3!) = 5: two left/right chains, two zig-zag shapes, and one balanced tree.
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