Which sequence is the pre-order traversal of the BST formed by inserting the…

2018

Which sequence is the pre-order traversal of the BST formed by inserting the following keys in the given order?
9, 8, 12, 22, 4, 10, 13

  1. A.

    8, 9, 4, 12, 10, 22, 13

  2. B.

    9, 8, 4, 12, 22, 10, 13

  3. C.

    9, 8, 4, 12, 10, 22, 13

  4. D.

    13, 22, 10, 12, 4, 8, 9

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Correct answer: C

Construct the BST by inserting the keys in the given order:

1. 9 becomes the root.
2. 8 is inserted to the left of 9.
3. 12 is inserted to the right of 9.
4. 22 is inserted to the right of 12.
5. 4 is inserted to the left of 8.
6. 10 is inserted to the left of 12.
7. 13 is inserted to the left of 22.

Now take pre-order traversal: root, left subtree, right subtree.

Pre-order = 9, 8, 4, 12, 10, 22, 13.

Correct Answer: Option C.

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