Data Structures | Binary Trees | Question 14

Consider the following nested representation of binary trees: (X Y Z) indicates Y and Z are the left and right sub stress, respectively, of node X. Note that Y and Z may be NULL, or further nested. Which of the following represents a valid binary tree?
(A) (1 2 (4 5 6 7))
(B) (1 (2 3 4) 5 6) 7)
(C) (1 (2 3 4)(5 6 7))
(D) (1 (2 3 NULL) (4 5))

Answer: (C)
Explanation: C is fine.

(1 (2 3 4)(5 6 7))  represents following binary tree
      1
   /    \
  2      5 
 / \    / \
3   4  6   7

A) (1 2 (4 5 6 7)) is not fine as there are 4 elements in one bracket.

B) (1 (2 3 4) 5 6) 7) is not fine as there are 2 opening brackets and 3 closing.

D) (1 (2 3 NULL) (4 5)) is not fine one bracket has only two entries (4 5)

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