# Data Structures - Stacks

21:

Stack A has the eintries a, b, c (with a on top), Stack B is empty. An entry popped out of stack A can be printed immediately or pushed to stack B. An entry popped out of stack B can only be printed. In the arrangement, which of the following permutations of a, b, c is not possible?

 A. b a c B. b c a C. c a  b D. a b c Answer Report Discuss Option: C Explanation : Click on Discuss to view users comments. Write your comments here:
22:

The postfix equivalent of the prefix * + a b - c d is

 A. ab+cd-* B. ab cd + - * C. ab + cd * - D. ab + - cd * Answer Report Discuss Option: A Explanation : The tree whose preorder traversal yields * + A B – C D, is given in fig 6.18. Writer the post-order traversal of the tree. That is the postfix form. Click on Discuss to view users comments. Rishi said: (12:26am on Sunday 23rd June 2013) Prefix Form : * ab-cdInfix Form : (a b)*(c-d)Postfix Form : ab cd-* Write your comments here:
23:

Stacks cannot be used to

 A. eevaluate an arithmetic expression  in postfix form B. iumplemen recursion C. convert a given arithmetic expression in infix form to its equivalent postfix form D. allocate resources (like CPU) by the operating system Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Write your comments here:
24:

The postifx expression for the infix expression

A + B* (C+D) / F + D*E is

 A. AB+CD + *F/ D+E* B. ABCD + *F / + DE* + C. A*B + CD / F* DE ++ D. A + *BCD/ F* DE ++ Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Write your comments here:
25:

Stack is useful for implemeting

 A. breadth first search B. depth first search C. recursion D. Both (b) & (c) Answer Report Discuss Option: D Explanation : Breadth first search  needs Queue for implementaion    Click on Discuss to view users comments. Write your comments here: