# Date Structure question and answer

13. What are the notations used in Evaluation of Arithmetic Expressions using prefix and postfix forms?
Polish and Reverse Polish notations.

14. Minimum number of queues needed to implement the priority queue?
Two. One queue is used for actual storing of data and another for storing priorities.

15. Convert the expression ((A + B) * C - (D - E) ^ (F + G)) to equivalent Prefix and Postfix notations.

1. Prefix Notation: - * +ABC ^ - DE + FG
2. Postfix Notation: AB + C * DE - FG + ^ -

16. Sorting is not possible by using which of the following methods? (Insertion, Selection, Exchange, Deletion)
Sorting is not possible in Deletion. Using insertion we can perform insertion sort, using selection we can perform selection sort, using exchange we can perform the bubble sort (and other similar sorting methods). But no sorting method can be done just using deletion.

17. In tree construction which is the suitable efficient data structure? (Array, Linked list, Stack, Queue)
Linked list is the suitable efficient data structure.

18. What is the type of the algorithm used in solving the 8 Queens problem?
Backtracking.