# Data Structures - Stacks

16:   Stack can't be used to
 A. Evaluate an arithmetic expression in postfix form B. Implement recursion C. Convert a given arithmetic expression in infix form to its evaluate 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:
17:   Which of the following permutations can be obtained in the output(in the same order),using a stack assuming that the input is the sequence 1,2,3,4,5 in that order?
 A. 3,4,5,1,2 B. 3,4,5,2,1 C. 1,5,2,3,4 D. 5,4,3,2,1 Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. devendra said: (8:50am on Friday 13th September 2013) correct answer is D Write your comments here:
18:   Stack is useful for implementing
19:

If the sequence of operations- push (1), push (2), pop, push (1), push (2), pop, pop, pop, push (2), pop, are performed on a stack, the sequenceof popped out values are

 A. 2, 2, 1, 1, 2 B. 2, 2, 1, 2, 2 C. 2, 1, 2, 2, 1 D. 2, 1, 2, 2, 2 Answer Report Discuss Option: A Explanation : Click on Discuss to view users comments. Write your comments here:
20:

In evaluating the arithmetic expression 2 * 3-(4+5), using stacks to evaluate its equivalent post-fix form, which of the following stack configuration is not possible?

 A. B. C. D. Answer Report Discuss Option: D Explanation : The postfix equivalent is 2 3 * 4 5 + -. For evaluating this using stack, starting from the left, we have to scan one by one. If it is an operand push. if it is an operator, pop it twice, apply the operator on the popped out entries and push the result onto the stack. If we follow this, we can find configuration in option (d) is not possible. Click on Discuss to view users comments. Write your comments here:

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