GATE CSE 2017 Set 2 | Question: 36

Question

The pre-order traversal of a binary search tree is given by $12, 8, 6, 2, 7, 9, 10, 16, 15, 19, 17, 20$. Then the post-order traversal of this tree is

• A. $2, 6, 7, 8, 9, 10, 12, 15, 16, 17, 19, 20$
• B. $2, 7, 6, 10, 9, 8, 15, 17, 20, 19, 16, 12$
• C. $7, 2, 6, 8, 9, 10, 20, 17, 19, 15, 16, 12$
• D. $7, 6, 2, 10, 9, 8, 15, 16, 17, 20, 19, 12$

Comments

ans is B

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Should we need to create a in order... Can we just make a tree by using bst properties???

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Yes we can construct a unique BST by given exactly one of postorder/preorder using BST properties. No need to find inorder.

@rahul your method will not work in this question: https://gateoverflow.in/3816/gate-it-2005-question-55

Answer 1

B) is the answer