Kshema Placement Paper -: Data Structure Questions And Answers

Kshema Previous Years Solved Sample Placement Papers

1. When an operand is read, which of the following is done?

   a) It is placed on to the output

   b) It is placed in operator stack

   c) It is ignored

   d) Operator stack is emptied

   Answer: a

   Explanation: While converting an infix expression to a postfix expression, when an operand is read, it is placed on to the output. When an operator is read, it is placed in the operator stack.

2. What should be done when a left parenthesis ‘(‘ is encountered?

   a) It is ignored

   b) It is placed in the output

   c) It is placed in the operator stack

   d) The contents of the operator stack is emptied

   Answer: c

   Explanation: When a left parenthesis is encountered, it is placed on to the operator stack. When the corresponding right parenthesis is encountered, the stack is popped until the left parenthesis and remove both the parenthesis.

3. Which of the following is an infix expression?

   a) (a+b)*(c+d)

   b) ab+c*

   c) +ab

   d) abc+*

   Answer: a

   Explanation: (a+b)*(c+d) is an infix expression. +ab is a prefix expression and ab+c* is a postfix expression.

4. What is the time complexity of an infix to postfix conversion algorithm?

   a) O(N log N)

   b) O(N)

   c) O(N²)

   d) O(M log N)

   Answer: b

   Explanation: The time complexity of an infix to postfix expression conversion algorithm is mathematically found to be O(N).

5. What is the postfix expression for the corresponding infix expression?

   a+b*c+(d*e)

   a) abc*+de*+

   b) abc+*de*+

   c) a+bc*de+*

   d) abc*+(de)*+

   Answer: a

   Explanation: Using the infix to postfix expression conversion algorithm, the corresponding postfix expression is found to be abc*+de*+.

6. Parentheses are simply ignored in the conversion of infix to postfix expression.

   a) True

   b) False

   Answer: b

   Explanation: When a parenthesis is encountered, it is placed on the operator stack. When the corresponding parenthesis is encountered, the stack is popped until the other parenthesis is reached and they are discarded.

7. It is easier for a computer to process a postfix expression than an infix expression.

   a) True

   b) False

   Answer: a

   Explanation: Computers can easily process a postfix expression because a postfix expression keeps track of precedence of operators.

8. What is the postfix expression for the infix expression?

   a-b-c

   a) -ab-c

   b) ab – c –

   c) – -abc

   d) -ab-c

   Answer: b

   Explanation: The corresponding postfix expression for the given infix expression is found to be ab-c- and not abc- -.

9. What data structure is used when converting an infix notation to prefix notation?
   (a) Stack
   (b) Queue
   (c) B-Trees
   (d) Linked-list
   Answer: (a)
   Explanation: To convert infix to prefix, reverse the equation and use the infix-to-postfix algorithm. This process utilizes stacks for operator precedence and association.

10. What will the following program do?

    void main()
    {
        int i;
        char a[] = "String";
        char *p = "New String";
        char *Temp;
        Temp = a;
        a = malloc(strlen(p) + 1);
        strcpy(a, p); // Line number: 9
        p = malloc(strlen(Temp) + 1);
        strcpy(p, Temp);
        printf("(%s, %s)", a, p);
        free(p);
        free(a);
    } // Line number 15
            

    (a) Swap contents of p & a and print: (New string, string)

    (b) Generate compilation error in line number 8 (Ans)

    (c) Generate compilation error in line number 5

    (d) Generate compilation error in line number 7

    (e) Generate compilation error in line number 1

11. In the following code segment, what will be the result of the function?

    Value of x , value of y
    {
        unsigned int x = -1;
        int y;
        y = ~0;
        if(x == y)
            printf("same");
        else
            printf("not same");
    }
            

    (a) same, MAXINT, -1 (Ans)

    (b) not same, MAXINT, -MAXINT

    (c) same, MAXUNIT, -1

    (d) same, MAXUNIT, MAXUNIT

    (e) not same, MAXINT, MAXUNIT

12. What will be the result of the following program?

    char *gxxx()
    {
        static char xxx[1024];
        return xxx;
    }
    
    main()
    {
        char *g = "string";
        strcpy(gxxx(), g);
        g = gxxx();
        strcpy(g, "oldstring");
        printf("The string is : %s", gxxx());
    }
            

    (a) The string is : string

    (b) The string is : Oldstring (Ans)

    (c) Run time error/Core dump

    (d) Syntax error during compilation

    (e) None of these