Sunday, November 13, 2011

CS301 Midterm Past Solved Paper (3)


MIDTERM  EXAMINATION
Fall 2009
CS301- Data Structures (Session - 5)
Ref No: 885482
Time: 60 min
Marks: 38

   
Question No: 1    ( Marks: 1 )    - Please choose one
  
Which one of the following is a valid postfix expression?

       ► ab+c*d-
       ► abc*+d-
       ► abc+*d-
       ► (abc*)+d-
   
Question No: 2    ( Marks: 1 )    - Please choose one
  
The tree data structure is a 

       ► Linear data structure
       ► Non-linear data structure
       ► Graphical data structure
       ► Data structure like queue
   
Question No: 3    ( Marks: 1 )    - Please choose one
  
A Compound Data Structure is the data structure which can have multiple data items of same type or of different types. Which of the following can be considered compound data structure?

       ► Arrays

       ► LinkLists

       ► Binary Search Trees

       ► All of the given options

   
Question No: 4    ( Marks: 1 )    - Please choose one
 Suppose a pointer has been declared in main but has not assigned any variable address then

►That pointer points to First byte in main function

►That pointer contains a NULL value

►None of these


►That pointer points to any memory address

   
Question No: 5    ( Marks: 1 )    - Please choose one
  
Here is the start of a C++ class declaration:

class foo
    {
    public:
      void x(foo f);
      void y(const foo f);
      void z(foo f) const;
      ...

Which of the three member functions can alter the PRIVATE member variables of the foo object that activates the function?


►Only x can alter the private member variables of the object that activates the function.
►Only y can alter the private member variables of the object that activates the function.

►Only z can alter the private member variables of the object that activates the function.
►Two of the functions can alter the private member variables of the object that activates the function.

   
Question No: 6    ( Marks: 1 )    - Please choose one
  
The operation for removing an entry from a stack is traditionally called:                            
       ► delete
       ► peek
       ► pop
       ► remove
   
Question No: 7    ( Marks: 1 )    - Please choose one
  
Which statement of the following statements is incorrect?
       ► Lists can be implemented by using arrays or linked lists

       ► A list is a sequence of one or more data items
       ► Stack is a special kind of list in which all insertions and deletions take place at one end
       ► Stacks are easier to implement than lists

   
Question No: 8    ( Marks: 1 )    - Please choose one
 Parameters in function call are passed using,

       ► Stack

       ► Queue

       ► Binary Search Tree

       ► AVL Tree

   
Question No: 9    ( Marks: 1 )    - Please choose one
  
Consider the following sequence of push operations in a stack:      
stack.push(’7’);
stack.push(’8’);
stack.push(’9’);
stack.push(’10’);
stack.push(’11’);
stack.push(’12’);

►7 8 9 10 11 12
►9 8 11 10 7 12
►9 10 8 11 12 7
►9 10 8 12 7 11
   
Question No: 10    ( Marks: 1 )    - Please choose one
  
What is the maximum depth of recursive calls a function may make?

       ► 1
       ► 2
       ► n (where n is the argument)
       ► There is no fixed maximum
   
Question No: 11    ( Marks: 1 )    - Please choose one

 
 Consider the following function:

void test_a(int n)
{
cout << n << " ";
if (n>0)
test_a(n-2);
}

What is printed by the call test_a(4)?

       ► 4 2
       ► 0 2 4
       ► 0 2

       ► 2 4

   
Question No: 12    ( Marks: 1 )    - Please choose one
 Queue follows,

       ► Last in First out

       ► First in Last out

       ► First in First out

       ► None of these

   
Question No: 13    ( Marks: 1 )    - Please choose one
 _________ is a binary tree where every node has a value, every node's left subtree contains only values less than or equal to the node's value, and every node's right subtree contains only values that are greater then or equal ?                                                                    
►Strictly Binary Tree
►Binary Search tree

►AVL tree

►All of these
   
Question No: 14    ( Marks: 1 )    - Please choose one
  
Four statements about trees are below. Three of them are correct. Which one is INCORRECT?
►Trees are recursively defined multi-dimensional data structures
►The order of a tree indicates a maximum number of childen allowed at each node of the tree
►A search tree is a special type of tree where all values (i.e. keys) are ordered

►If Tree1's size is greater than Tree2's size, then the height of Tree1 must also be greater than Tree2's height.
   
Question No: 15    ( Marks: 1 )    - Please choose one
 Below is a binary search tree. If we delete the value 50 using the algorithm we discussed, what value will be in the root of the remaining tree?
       ► 50
       ► 60
       ► 70
       ► 80
   
Question No: 16    ( Marks: 1 )    - Please choose one
 _________ is a data structure that can grow easily dynamically at run time without having to copy existing elements.

       ► Array

       ► List

       ► Both of these 

       ► None of these

   
Question No: 17    ( Marks: 1 )
 Give the names of basic Queue Operations
Ans:
Definition: A collection of items in which only the earliest added item may be accessed. Basic operations are add (to the tail) or enqueue and delete (from the head) or dequeue. Delete returns the item removed. Also known as "first-in, first-out" or FIFO.
   
Question No: 18    ( Marks: 1 )
  
Give one benefit of using Stack.
In computer science, a stack is a last in, first out (LIFO) abstract data type and data structure. A stack can have any abstract data type as an element, but is characterized by only two fundamental operations: push and pop. the data structure itself enforces the proper order of calls.
   
Question No: 19    ( Marks: 2 )
  
Let’s call the node as a that requires re-balancing. Consider the two cases given below:
 1) An insertion into left subtree of the left child of a
 2) An insertion into right subtree of the right child of a.

Which of the following statement is correct about these two cases. 

1) The insertion occurs outside (i.e., left-left or right-right) in cases 1 and 2. single rotation can fix the balance in these two cases. 
2) The insertion occurs inside ((i.e., left-left or right-right) in cases 1 and 2. single rotation cannot fix the balance in these two cases 

   
Question No: 20    ( Marks: 3 )
  
Consider the following sequence of push operations in a stack:                 

stack.push(’1’);
stack.push(’2’);
stack.push(’3’);
stack.push(’4’);
stack.push(’5’);
stack.push(’6’);

You can insert as many stack.pop()’s as you like in the above sequence of stack.push’s to get a desired output. Which of the following cannot be an output?
A. 123456
B. 325416
C. 342561
D. 342615
E. 342165

    
Question No: 21    ( Marks: 5 )
 

 Give short answers of the following questions:

1.      Why List wastes less memory as compared to Arrays.


Ans:
1.  Linked lists do not need contiguous blocks of memory; extremely large data sets stored in an array might not be able to fit in memory.
   2. Linked list storage does not need to be preallocated (again, due to arrays needing contiguous memory blocks).
   3. Inserting or removing an element into a linked list requires one data update, inserting or removing an element into an array requires n (all elements after the modified index need to be shifted).

Array is a collection of same data type. In linked list there are two field one is address and other is pointer. In array elements are arranged in a specific order

2.      Why we can change the size of list after its creation when we can not do that in simple arrays.
   Some how the answer will be same as part 1 because Inserting or removing an element into a linked list requires one data update, inserting or removing an element into an array requires n (all elements after the modified index need to be shifted).

Array is a collection of same data type. The size of array is mentioned with its declaration. in arrays the elements are in contiguous position. one must after another. while in linked list we gave the address of next element in the next part of node.

   
Question No: 22    ( Marks: 10 )
  
Convert the following infix expression into postfix expressions using stack (Show complete steps)

1-2 ­3­3-(4+5*6)*7
Step 1
Post fix
stack
1
1

-

-
2
2


12
-


































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