InFix PreFix and PostFix MCQs

Question 1. The postfix form of the expression (A+ B)*(C*D- E)*F / G is?
a) AB+ CD*E - FG /**
b) AB + CD* E - F **G /
c) AB + CD* E - *F *G /
d) AB + CDE * - * F *G /

ANSWER: a) AB+ CD*E - FG /**

Question 2. The data structure required to check whether an expression contains balanced parenthesis is?
a) Stack
b) Queue
c) Array
d) Tree

ANSWER: a) Stack

Question 3. What data structure would you mostly likely see in a non recursive implementation of a recursive algorithm?
a) LinkList
b) Stack
c) Queue
d) Tree
ANSWER: b) Stack

Question 4. The process of accessing data stored in a serial access memory is similar to manipulating data on a ------?
a) Heap
b) Binary Tree
c) Array
d) Stack
ANSWER: d) Stack

Question 5. The postfix form of A*B+C/D is?
a) *AB/CD+
b) AB*CD/+
c) A*BC+/D
d) ABCD+/*
ANSWER: b) AB*CD/+

Question 6. Which data structure is needed to convert infix notation to postfix notation?

a) Branch
b) Tree
c) Queue
d) Stack
ANSWER: d) Stack

Question 7. The prefix form of A-B/ (C * D ⋀ E) is?

a) -/*⋀ACBDE
b) -ABCD*⋀DE
c) -A/B*C⋀DE
d) -A/BC*⋀DE
ANSWER: c) -A/B*C⋀DE

Question 8. What is the result of the following operation
Top (Push (S, X))
a) X
b) Null
c) S
d) None
ANSWER: a) X

Question 9. The prefix form of an infix expression p + q - r * t is?

a) + pq - *rt
b) - +pqr * t
c) - +pq * rt
d) - + * pqrt
ANSWER: c) - +pq * rt

Question 10. Which data structure is used for implementing recursion?
a) Queue
b) Stack
c) Array
d) List
ANSWER: b) Stack

Question 11. The result of evaluating the postfix expression 5, 4, 6, +, *, 4, 9, 3, /, +, * is?
a) 600
b) 350
c) 650
d) 588
ANSWER: b) 350

Question 12. Convert the following infix expressions into its equivalent postfix expressions
(A + B ⋀D)/(E - F)+G
a) (A B D ⋀ + E F - / G +)
b) (A B D +⋀ E F - / G +)
c) (A B D ⋀ + E F/- G +)
d) None
ANSWER: a) (A B D ⋀ + E F - / G +)

Question 13. Convert the following Infix expression to Postfix form using a stack
x + y * z + (p * q + r) * s, Follow usual precedence rule and assume that the expression is legal.
a) xyz*+pq*r+s*+
b) xyz*+pq*r+s+*
c) xyz+*pq*r+s*+
d) none
ANSWER: a) xyz*+pq*r+s*+

Question 14. Which of the following statement(s) about stack data structure is/are NOT correct?
a) Stack data structure can be implemented using linked list
b) New node can only be added at the top of the stack
c) Stack is the FIFO data structure
d) The last node at the bottom of the stack has a NULL link
ANSWER: c) Stack is the FIFO data structure

Question 15. Consider the linked list implementation of a stack. Which of the following node is considered as Top of the stack?

a) First node
b) Last node
c) Any node
d) Middle node
ANSWER: a) First node

Question 16. Consider the following operation performed on a stack of size 5.
Push(1);
Pop();
Push(2);
Push(3);
Pop();
Push(4);
Pop();
Pop();
Push(5);
After the completion of all operation, the no of element present on stack are
a) 1
b) 2
c) 3
d) 4
ANSWER: a) 1

Question 17. Which of the following is not an inherent application of stack?
a) Reversing a string
b) Evaluation of postfix expression
c) Implementation of recursion
d) Job scheduling
ANSWER: d) Job scheduling

Question 18. Which of the following operation take worst case linear time in the array implementation of stack?
a) Push
b) Pop
c) IsEmpty
d) None
ANSWER: d) None

Question 19. The type of expression in which operator succeeds its operands is?
a) Infix Expression
b) pre fix Expression
c) postfix Expression
d) None
ANSWER: c) postfix Expression

Question 20. Which of the following application generally use a stack?
a) Parenthesis balancing program
b) Syntax analyzer in compiler
c) Keeping track of local variables at run time
d) All of the above
ANSWER: d) All of the above

Question 21. Consider the following array implementation of stack:
#define MAX 10
Struct STACK
{
Int arr [MAX];
Int top = -1;
}
If the array index starts with 0, the maximum value of top which does not cause stack overflow is?
a) 8
b) 9
c) 10
d) 11
ANSWER: a) 8

Question 22. What is the minimum number of stacks of size n required to implement a queue of size n?
a) One
b) Two
c) Three
d) Four
ANSWER: b) Two

Question 23. Assume that the operators +,-, X are left associative and ⋀ is right associative. The order of precedence (from highest to lowest) is ⋀, X, +, -. The postfix expression corresponding to the infix expression a + b X c – d ⋀ e ⋀ f is
a) abc X+ def ⋀ ⋀ -
b) abc X+ de⋀f⋀ -
c) ab+c Xd – e ⋀f⋀
d) -+aXbc⋀ ⋀def
ANSWER: a) abc X+ def ⋀ ⋀ -

Question 24. If the elements “A”, “B”, “C” and “D” are placed in a stack and are deleted one at a time, in what order will they be removed?
a) ABCD
b) DCBA
c) DCAB
d) ABDC
ANSWER: b) DCBA

Question 25. Consider the usual implementation of parentheses balancing program using stack. What is the maximum number of parentheses that will appear on stack at any instance of time during the analysis of ( ( ) ( ( ) ) ( ( ) ) )?
a) 1
b) 2
c) 3
d) 4
ANSWER: c) 3