1. The process of checking two items and determining which one is greater or smaller than the other.

2. It is the process of visiting all the nodes in a binary search tree in a specific order, such as in-order, pre-order and post-order.

3. The number of times two elements are compared during the sorting process.

4. The time or space complexity of an algorithm when it receives average inputs.

5. It is the point in the search interval that divides it into two equal halves.

6. A data type that can have one of two possible values, usually true or false.

7. A list that is not sorted according to any specific criterion.

8. A sort algorithm that arranges the elements of an array without needing any extra memory for sorting.

9. It is the element being searched for in the binary search algorithm.

10. It is the length of the longest path from a node to a leaf in a binary search tree.

11. The process of combining two or more sorted sub-arrays into a single sorted array.

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12. The time taken to execute an algorithm or program.

13. It is a fundamental unit of a binary search tree that contains a value and links to its children.

14. It is a traversing method for binary search trees where the left subtree is recursively traversed, followed by the root, and then the right subtree.

15. The speed and effectiveness with which a task is completed, measured in terms of time and resources used.

16. It is a traversing method for binary search trees where the left and right subtrees are first recursively traversed, followed by the root.

17. The time or space complexity of an algorithm when it receives the worst input possible.

18. A sorting order in which the items are arranged from smallest to largest.

19. The time or space complexity of an algorithm when it receives the best input possible.