Digital Globalsoft Placement Paper - Data Structure Questions And Answers

Digital Globalsoft Previous Years Solved Sample Placement Papers

1. What is the corresponding postfix expression for the given infix expression? a*(b+c)/d

   A) ab*+cd/

   B) ab+*cd/

   C) abc*+/d

   D) abc+*d/ (Ans)

2. What is the corresponding postfix expression for the given infix expression? a+(b*c(d/e^f)*g)*h)

   A) ab*cdef/^*g-h+

   B) abcdef^/*g*h*+ (Ans)

   C) abcd*^ed/g*-h*+

   D) abc*de^fg/*-*h+

3. What is the correct postfix expression for the following expression? a+b*(c^d-e)^(f+g*h)-i

   A) abc^de-fg+*^*+i

   B) abcde^-fg*+*^h*+i

   C) abcd^e-fgh*+^*+i (Ans)

   D) ab^-dc*+ef^gh*+i

4. A Double-ended queue supports operations such as adding and removing items from both the sides of the queue. You are given only stacks to implement this data structure. How many stacks are required to implement the operation?

   A) 1

   B) 2 (Ans)

   C) 3

   D) 4

5. You are asked to perform a queue operation using a stack. Assume the size of the stack is some value �n� and there are �m� number of variables in this stack. What is the time complexity of performing the deQueue operation?

   A) O(m) (Ans)

   B) O(n)

   C) O(m*n)

   D) Data is insufficient

6. Consider you have an array of some random size. You need to perform dequeue operation. You can perform it using stack operations (push and pop) or using queue operations itself (enQueue and Dequeue). The output is guaranteed to be the same. Find some differences:

   A) They will have different time complexities (Ans)

   B) The memory used will not be different

   C) There are chances that the output might be different

   D) No differences

7. Consider you have a stack whose elements in it are as follows:

   5 4 3 2 << top

   Where the top element is 2. You need to get the following stack:

   6 5 4 3 2 << top

   The operations that need to be performed are (You can perform only push and pop):

   A) Push(pop()), push(6), push(pop()) (Ans)

   B) Push(pop()), push(6)

   C) Push(pop()), push(pop()), push(6)

   D) Push(6)

8. Why is the implementation of stack operations on queues not feasible for a large dataset (Assume the number of elements in the stack to be n)?

   A) Because of its time complexity O(n) (Ans)

   B) Because of its time complexity O(log(n))

   C) Extra memory is not required

   D) There are no problems

9. Consider yourself to be on a planet where the computational power of chips is slow. You have an array of size 10. You want to enqueue some elements into this array. Push and pop operations both take 1 second respectively. The total time required to perform an enqueue operation is:

   A) 20

   B) 40

   C) 42

   D) 43 (Ans)