Data Structures and Algorithms MCQ - Stacks

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

View Explanation
Comment

18 Stack is useful for implementing

A
Radix
B
Breadth-first search
C
Recursion
D
None of these

View Explanation
Comment

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 sequence of 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

View Explanation
Comment

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
https://cynorwebsolutions.com/attavo/showphoto.php?id=4073&what=option1Img
B
https://cynorwebsolutions.com/attavo/showphoto.php?id=4073&what=option2Img
C
https://cynorwebsolutions.com/attavo/showphoto.php?id=4073&what=option3Img
D
https://cynorwebsolutions.com/attavo/showphoto.php?id=4073&what=option4Img

View Explanation
Comment

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 the configuration in option (d) is not possible.