1. What's the difference between SQL, DDL, and DML?
  2. What's a join? An inner join? An outer join?
  3. Describe HTTP.
  4. What's a design pattern?
  5. Can you explain the singleton, vistor, facade, or handle class design pattern?
  6. When you do an ls -l, describe in detail everything that comes up on the screen.
  7. Tell me three ways to find an IP address on a Unix box.
  8. Write a bubble sort.
  9. Write a linked list.
  10. Describe an object.
  11. What does object-oriented mean to you.
  12. Can you explain what a B tree is?
  13. What's the difference between UDP and TCP?
  14. What is ICMP?
  15. What's the difference between a stack and a Queue?
  16. Do you know anything about the protection rings in the PC architecture?
  17. How much hardware/Assembler/Computer Architecture experience do you have.
  18. Explain final, finalize, and finally. When the finalize is invoked? How does GC work? etc.
  19. What is your experience with Servlet and JSP?
  20. What is the Prototype design pattern?
  21. In a system that you are designing and developing, a lot of small changes are expected to be committed at the end of a method call (persisted to the DB). If you don't want to query the database frequently. what would you do?
  22. Give an example in which you will combine several design patterns, and explain how the system can benefit from that.
  23. Why would you apply design patterns (benefits)?
  24. What is a two-phase commit?
  25. What will happen if one of your web-server or appserver crashs during its execution?
  26. What are various problems unique to distributed databases
  27. Describe the file system layout in the UNIX OS
  28. what is disk interleaving
  29. why is disk interleaving adopted
  30. given a new disk, how do you determine which interleaving is the best
  31. give 1000 read operations with each kind of interleaving determine the best interleaving from the statistics
  32. draw the graph with performace on one axis and 'n' on another, where 'n' in the 'n' in n-way disk interleaving. (a tricky question, should be answered carefully)
  33. Design a memory management scheme.
  34. What sort of technique you would use to update a set of files over a network, where a server contains the master copy.
  1. What is an object in C++?
  2. What is a message?
  3. What is a class?
  4. What is an instance?
  5. What is a super-class?
  6. What is inheritance?
  7. To what does message protocol refer?
  8. What is polymorphism?
  9. What are instance variables?
  10. What are class variables?
  11. What is a method?
  12. In C++ what is a constructor? A destructor?
  13. Compare and contrast C and C++.
  14. What is operator overloading?
  15. What is cin and cout?
  16. Contrast procedural and object oriented programming.
  17. How do you link a C++ program to C functions?
  18. Explain the scope resolution operator.
  19. What are the differences between a C++ struct and C++ class?
  20. How many ways are there to initialize an int with a constant?
  21. How does throwing and catching exceptions differ from using setjmp and longjmp?
  22. What is your reaction to this line of code?
    delete this;
  23. What is a default constructor?
  24. What is a conversion constructor?
  25. What is the difference between a copy constructor and an overloaded assignment operator?
  26. When should you use multiple inheritance?
  27. What is a virtual destructor?
  28. Explain the ISA and HASA class relationships. How would you implement each in a class design?
  29. When is a template a better solution than a base class?
  30. What is the result of compiling this program in a C compiler? in a C++ compiler?
    int __ = 0;
    main() {
    int ___ = 2;
    printf("%d\n", ___ + __);
    }
  31. What is the difference between C and C++ ? Would you prefer to use one over the other ?
  32. What are the access privileges in C++ ? What is the default access level ?
  33. What is data encapsulation ?
  34. What is inheritance ?
  35. What is multiple inheritance ? What are it's advantages and disadvantages ?
  36. What is polymorphism?
  37. What do the keyword static and const signify ?
  38. How is memory allocated/deallocated in C ? How about C++ ?
  39. What is UML ?
  40. What is the difference between a shallow copy and a deep copy ?
  41. What are the differences between new and malloc?
  42. What is the difference between delete and delete[]?
  43. What are the differences between a struct in C and in C++?
  44. What are the advantages/disadvantages of using #define?
  45. What are the advantages/disadvantages of using inline and const?
  46. What is the difference between a pointer and a reference?
  47. When would you use a pointer? A reference?
  48. What does it mean to take the address of a reference?
  49. What does it mean to declare a function or variable as static?
  50. What is the order of initalization for data?
  51. What is name mangling/name decoration?
  52. What kind of problems does name mangling cause?
  53. How do you work around them?
  54. What is a class?
  55. What are the differences between a struct and a class in C++?
  56. What is the difference between public, private, and protected access?
  57. For class CFoo { }; what default methods will the compiler generate for you>?
  58. How can you force the compiler to not generate them?
  59. What is the purpose of a constructor? Destructor?
  60. What is a constructor initializer list?
  61. When must you use a constructor initializer list?
  62. What is a: Constructor? Destructor? Default constructor? Copy constructor? Conversion constructor?
  63. What does it mean to declare a... member function as virtual? member function as static? member varible as static? destructor as static?
  64. Can you explain the term "resource acqusition is initialization?"
  65. What is a "pure virtual" member function?
  66. What is the difference between public, private, and protected inheritance?
  67. What is virtual inheritance?
  68. What is placement new?
  69. What is the difference between operator new and the new operator?
  70. What is exception handling?
  71. Explain what happens when an exception is thrown in C++.
  72. What happens if an exception is not caught?
  73. What happens if an exception is throws from an object's constructor?
  74. What happens if an exception is throws from an object's destructor?
  75. What are the costs and benefits of using exceptions?
  76. When would you choose to return an error code rather than throw an exception?
  77. What is a template?
  78. What is partial specialization or template specialization?
  79. How can you force instantiation of a template?
  80. What is an iterator?
  81. What is an algorithm (in terms of the STL/C++ standard library)?
  82. What is std::auto_ptr?
  83. What is wrong with this statement? std::auto_ptr ptr(new char[10]);
  84. It is possible to build a C++ compiler on top of a C compiler. How would you do this?
  85. What output does the following code generate? Why? What output does it generate if you make A::Foo() a pure virtual function?
  86. What output does this program generate as shown? Why?
  87. C++ ( what is virtual function ? what happens if an error occurs in constructor or destructor. Discussion on error handling, templates, unique features of C++. What is different in C++, ( compare with unix).
  88. I was given a c++ code and was asked to find out the bug in that. The bug was that he declared an object locally in a function and tried to return the pointer to that object. Since the object is local to the function, it no more exists after returning from the function. The pointer, therefore, is invalid outside.
  1. What does the term cast refer to? Why is it used?
  2. In arithmetic expressions, to what data type will the C compiler promote a character?
  3. What is the difference between a statement and a block?
  4. Increment the variable next three different ways.
  5. How is a comment formed in C.
  6. Can comments be nested?
  7. From the standpoint of programming logic, what is the difference between a loop with the test at the top, and a loop where the test is at the bottom?
  8. Specify the skeletons of two C loops with the test at the top.
  9. Specify a C loop with the test at the bottom.
  10. What is the switch statement?
  11. What does a break statement do? Which control structures use it?
  12. In a loop, what is the difference between a break and continue statement?
  13. Where may variables be defined in C?
  14. What is the difference between a variable definition and a variable declaration?
  15. What is the purpose of a function prototype?
  16. What is type checking?
  17. To what does the term storage class refer?
  18. List C's storage classes and what they signify.
  19. State the syntax for the printf() and scanf() functions. State their one crucial difference with respect to their parameters.
  20. With respect to function parameter passing, what is the difference between call-by-value and call-by-reference? Which method does C use?
  21. What is a structure and a union in C?
  22. Define a structure for a simple name/address record.
  23. What does the typedef keyword do?
  24. Use typedef to make a short-cut way to declare a pointer to the nameAddr structure above. Call it addrPtr.
  25. Declare a variable with addrPtr called address.
  26. Assuming the variable address above, how would one refer to the city portion of the record within a C expression?
  27. What is the difference between: #include and #include "stdio.h"
  28. What is #ifdef used for?
  29. How do you define a constant in C?
  30. Why can't you nest structure definitions?
  31. Can you nest function definitions?
  32. What is a forward reference?
  33. What are the following and how do they differ: int, long, float and double?
  34. Define a macro called SQR which squares a number.
  35. Is it possible to take the square-root of a number in C. Is there a square-root operator in C?
  36. Using fprintf() print a single floating point number right-justified in a field of 20 spaces, no leading zeros, and 4 decimal places. The destination should be stderr and the variable is called num.
  37. What is the difference between the & and && operators and the | and || operators?
  38. What is the difference between the -> and . operators?
  39. What is the symbol for the modulus operator?
  40. From the standpoint of logic, what is the difference between the fragment:
    if (next < max)
    next++;
    else
    next = 0;
    and the fragment:
    next += (next < max)? (1):(-next);
  41. What does the following fragment do?
    while((d=c=getch(),d)!=EOF&&(c!='\t'||c!=' '||c!='\b')) *buff++ = ++c; 
  42. Is C case sensitive (ie: does C differentiate between upper and lower case letters)?
  43. Specify how a filestream called inFile should be opened for random reading and writing. the file's name is in fileName.
  44. What does fopen() return if successful. If unsuccessful?
  45. What is the void data type? What is a void pointer?
  46. Declare a pointer called fnc which points to a function that returns an unsigned long.
  47. Declare a pointer called pfnc which points to a function that returns a pointer to a structure of type nameAddr.
  48. It is possible for a function to return a character, an integer, and a floating point number. Is it possible for a function to return a structure? Another function?
  49. What is the difference between an lvalue and an rvalue?
  50. Given the decimal number 27, how would one express it as a hexadecimal number in C?
  51. What is malloc()?
  52. What is the difference between malloc() and calloc()?
  53. What kind of problems was C designed to solve?
  54. write C code for deleting an element from a linked listy traversing a linked list efficient way of elimiating duplicates from an array
  55. Declare a void pointer
  56. Make the pointer aligned to a 4 byte boundary in a efficient manner
  57. What is a far pointer (in DOS)
  58. Write an efficient C code for 'tr' program. 'tr' has two command line arguments. They both are strings of same length. tr reads an input file, replaces each character in the first string with the corresponding character in the second string. eg. 'tr abc xyz' replaces all 'a's by 'x's, 'b's by 'y's and so on.
  59. Write C code to implement strtok() 'c' library function.
  60. Implement strstr(), strcpy(), strtok() etc
  61. Reverse a string.
  62. Given a linked list which is sorted, how will you insert in sorted way.
  63. Write a function that allocates memory for a two-dimensional array of given size (parameter x & y)
  64. Write source code for printHex(int i) in C/C++
  65. Write a function that finds the last instance of a character in a string.
  1. Write a function and the node data structure to visit all of the nodes in a binary tree.
  2. You know what a queue is .... Implement a queue class with Java. What is the cost of enqueue and dequeue? Can you improve this? What if the queue is full (I was using an looping array)? What kind of mechanism would you use to increase its size?
  3. Give an algorithm that calculates the distance between two text strings (only operations you can have are: delete, add, and change, one by one).
  4. Given the definition of a sequence (5 4 7 6 is, but 1 2 4 5 is not), write an algorithm to check if an arbitrary array is a sequence or not. Once I figured out a solution, I was asked to do a space and time complexity analysis.
  5. Describe a situation where concurrent access would lead to inconsistency in your application. How would you solve this problem?
  6. You are given a list of n numbers from 1 to n-1, with one of the numbers repeated. Devise a method to determine which number is repeated.
  7. Write an algorithm to detect loop in a linked list.
  8. Given the time, devise an algorithm to calculate the angle between the hour and minute hands of an analog clock.
  9. Devise an algorithm for detecting whether a given string is a palindrome (spelled the same way forwards and backwards). For example, "A man, a plan, a canal, Panama."
  10. Given an eight-bit bitmap graphics file, devise an algorithm to convert the file into a two-bit ASCII approximation.
  11. Reverse a linked list.
  12. Insert in a sorted list
  13. First some definitions for this problem: a) An ASCII character is one byte long and the most significant bit in the byte is always '0'. b) A Kanji character is two bytes long. The only characteristic of a Kanji character is that in its first byte the most significant bit is '1'. Now you are given an array of a characters (both ASCII and Kanji) and, an index into the array. The index points to the start of some character. Now you need to write a function to do a backspace (i.e. delete the character before the given index).
  14. Delete an element from a doubly linked list.
  15. Write a function to find the depth of a binary tree.
  16. Assuming that locks are the only reason due to which deadlocks can occur in a system. What would be a foolproof method of avoiding deadlocks in the system.
  17. Besides communication cost, what is the other source of inefficiency in RPC?
  18. Ways of optimizing symbol table storage in compilers.
  19. A walk-through through the symbol table functions, lookup() implementation etc - The interv. was on the Microsoft C team.
  20. Given an array t[100] which contains numbers between 1..99. Return the duplicated value. Try both O(n) and O(n-square).
  21. Given an array of characters. How would you reverse it. ? How would you reverse it without using indexing in the array.
  22. Given a sequence of characters. How will you convert the lower case characters to upper case characters. ( Try using bit vector - sol given in the C lib -> typec.h)
  23. Give a good data structure for having n queues ( n not fixed) in a finite memory segment. You can have some data-structure separate for each queue. Try to use at least 90% of the memory space.
  24. Do a breadth first traversal of a tree.
  25. Given a list of numbers ( fixed list) Now given any other list, how can you efficiently find out if there is any element in the second list that is an element of the first list (fixed list).
  26. What is a balanced tree
  27. How would you find a cycle in a linked list? Try to do it in O(n) time. Try it using a constant amount of memory.
  28. Implement an algorithm to reverse a doubly linked list.
  29. A square picture is cut into 16 squares and they are shuffled. Write a program to rearrange the 16 squares to get the original big square.
  30. The Web can be modeled as a directed graph. Come up with a graph traversal algorithm. Make the algorithm non-recursive and breadth-first.
  31. How would you implement a hash table ? How do you deal with collisions?
  32. How would you find a cycle in a linked list? Try to do it in O(n) time. Try it using a constant amount of memory.
  33. Given a history of URLs, how would you determine if a particular URL had been seen before?
  34. Since pages can have multiple URLs pointing to them, how can you make sure you've never seen the same CONTENT before?
  35. Write a function to print all of the permutations of a string.
  36. Come up with the plan on how to traverse a graph, as well as to quickly determine if a given URL is one of the million or so you've previously seen.
  37. The Web can be modeled as a directed graph. Come up with a graph traversal algorithm. Make the algorithm non-recursive and breadth-first.
  38. Implement an algorithm to reverse a singly linked list. (with and without recursion)
  39. Implement an algorithm to reverse a doubly linked list.
  40. Implement an algorithm to insert in a sorted list.
  41. Delete an element from a doubly linked list.
  42. Write a function to copy two strings, A and B. The last few bytes of string A overlap the first few bytes of string B.
  43. Implement an algorithm to sort an array.
  44. Given a sequence of characters, how will you convert the lower case characters to upper case characters?
  45. Write a routine that prints out a 2-D array in spiral order.
  46. Count the number of set bits in a number without using a loop.
  47. Give me an algorithm and C code to shuffle a deck of cards, given that the cards are stored in an array of ints. Try to come up with a solution that does not require any extra space.
  48. Write a function that takes in a string parameter and checks to see whether or not it is an integer, and if it is then return the integer value.
  49. How would you print out the data in a binary tree, level by level, starting at the top?
  50. Given an array of characters which form a sentence of words, give an efficient algorithm to reverse the order of the words in it.
  51. Write a function to find the depth of a binary tree.
  52. Given a list of numbers ( fixed list) Now given any other list, how can you efficiently find out if there is any element in the second list that is an element of the first list (fixed list).
  53. How would you implement a queue from a stack?
  54. Write a funtion that finds repeating characters in a string.
  55. Write a routine to reverse a series of numbers without using an array.
  56. Give me an algorithm for telling me the number I didn't give you in a given range of numbers. (Numbers are given at random)
  1. Write a routine to draw a circle (x ** 2 + y ** 2 = r ** 2) without making use of any floating point computations at all.
  2. Given only putchar (no sprintf, itoa, etc.) write a routine putlong that prints out an unsigned long in decimal.
  3. Give a one-line C expression to test whether a number is a power of 2. [No loops allowed - it's a simple test.]
  4. Give a very good method to count the number of ones in a 32 bit number. (caution: looping through testing each bit is not a solution).
  5. What are the different ways to say, the value of x can be either a 0 or a 1.
  6. I was given two lines of assembly code which found the absolute value of a number stored in two's complement form. I had to recognize what the code was doing.
  7. Give a fast way to multiply a number by 7.
  8. Write an efficient algo and C code to shuffle a pack of cards.. this one was a feedback process until we came up with one with no extra storage.
  9. A real life problem - A square picture is cut into 16 sqaures and they are shuffled. Write a program to rearrange the 16 squares to get the original big square.
  10. Consider the base -2 representation of numbers. (-2 instead of usual +2). Give the condition for a number represented in this form to be positive? Also, if P(A, B) is a function that takes two 0-1 strings A,B in this representation, when can we say that P(A,B) returns the sum of these two numbers?
  11. Given an expression tree with no parentheses in it, write the program to give equivalent infix expression with parentheses inserted where necessary.
  12. Given a maze with cheese at one place and a mouse at some entrance, write a program to direct the mouse to cheese correctly. (Assume there is a path). Following primitives are given: moveforward, turnright, turnleft, iswall?, ischeese?, eatcheese.
  13. Give me an algorithm and C code to find the subarray with the largest sum given an array containing both positive and negative integers.
  14. Write a function that returns the factorial of a number.
  15. Write a function that computes the nth number in the Fibonacci sequence.
  16. Write an implementation of strlen().
  17. Switch the integer values stored in two registers without using any additional memory.
  18. Given two strings S1 and S2. Delete from S2 all those characters which occur in S1 also and finally create a clean S2 with the relevant characters deleted.
  19. Write a small lexical analyzer - interviewer gave tokens. expressions like "a*b" etc.
  20. Write a routine that prints out a 2-D array in spiral order!
  21. How is the readers-writers problem solved? - using semaphores/ada .. etc.
  22. Write code for reversing a linked list.
  23. Write, efficient code for extracting unique elements from a sorted list of array. e.g. (1, 1, 3, 3, 3, 5, 5, 5, 9, 9, 9, 9) -> (1, 3, 5, 9).
  1. Given a rectangular (cuboidal for the puritans) cake with a rectangular piece removed (any size or orientation), how would you cut the remainder of the cake into two equal halves with one straight cut of a knife ?
  2. You're given an array containing both positive and negative integers and required to find the subarray with the largest sum (O(N) a la KBL). Write a routine in C for the above.
  3. Given an array of size N in which every number is between 1 and N, determine if there are any duplicates in it. You are allowed to destroy the array if you like.
  4. Given an array of characters which form a sentence of words, give an efficient algorithm to reverse the order of the words (not characters) in it.
  5. How many points are there on the globe where by walking one mile south, one mile east and one mile north you reach the place where you started.
  6. In a X's and 0's game (i.e. TIC TAC TOE) if you write a program for this give a fast way to generate the moves by the computer. I mean this should be the fastest way possible.
  7. A version of the "There are three persons X Y Z, one of which always lies"..
  8. There are 3 ants at 3 corners of a triangle, they randomly start moving towards another corner.. what is the probability that they don't collide.
  9. If you are on a boat and you throw out a suitcase, Will the level of water increase.
  10. There are 4 men who want to cross a bridge. They all begin on the same side. You have 17 minutes to get all of them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown, etc. Each man walks at a different speed. A pair must walk together at the rate of the slower mans pace.
    Man 1:1 minute to cross
    Man 2: 2 minutes to cross
    Man 3: 5 minutes to cross
    Man 4: 10 minutes to cross
  11. You have 5 jars of pills. Each pill weighs 10 gram, except for contaminated pills contained in one jar, where each pill weighs 9 gm. Given a scale, how could you tell which jar had the contaminated pills in just one measurement?
  12. One train leaves Los Angeles at 15 MPH heading for New York. Another train leaves from New York at 20mph heading for Los Angeles on the same track. If a bird, flying at 25mph, leaves from Los Angeles at the same time as the train and flies back and forth between the two trains until they collide, how far will the bird have traveled?
  13. Imagine that you have 26 constants, labelled A through Z. Each constant is assigned a value in the following way: A = 1; the rest of the values equal their position in the alphabet (B corresponds to the second position so it equals 2, C = 3, etc.) raised to the power of the preceeding constant value. So, B = 2 ^ (A's value), or B = 2^1 = 2. C = 3^2 = 9. D = 4^9, etc., etc. Find the exact numerical value to the following equation:
    (X - A) * (X - B) * (X - C) * ... * (X - Y) * (X - Z) 
  14. You have 12 balls. All of them are identical except one, which is either heavier or lighter than the rest - it is either hollow while the rest are solid, or solid while the rest are hollow. You have a simple two-armed scale, and are permitted three weighings. Can you identify the odd ball, and determine whether it is hollow or solid.
  1. Which type of architecture 8085 has?
  2. How many memory locations can be addressed by a microprocessor with 14 address lines?
  3. 8085 is how many bit microprocessor?
  4. Why is data bus bi-directional?
  5. What is the function of accumulator?
  6. What is flag, bus?
  7. What are tri-state devices and why they are essential in a bus oriented system?
  8. Why are program counter and stack pointer 16-bit registers?
  9. What does it mean by embedded system?
  10. What are the different addressing modes in 8085?
  11. What is the difference between MOV and MVI?
  12. What are the functions of RIM, SIM, IN?
  13. What is the immediate addressing mode?
  14. What are the different flags in 8085?
  15. What happens during DMA transfer?
  16. What do you mean by wait state? What is its need?
  17. What is PSW?
  18. What is ALE? Explain the functions of ALE in 8085.
  19. What is a program counter? What is its use?
  20. What is an interrupt?
  21. Which line will be activated when an output device require attention from CPU?
http://www.javaprepare.com/quests/question.html

Puzzles, Riddles and Others

0. Classic: If a bear walks one mile south, turns left and walks one mile to the east and then turns left again and walks one mile north and arrives at its original position, what is the color of the bear.

ANS. The color of the bear is trivial. The possible solutions to it are interesting. In addition to the trivial north pole, there are additional circles near south pole. Think it out.

* 1. Given a rectangular (cuboidal for the puritans) cake with a rectangular piece removed (any size or orientation), how would you cut the remainder of the cake into two equal halves with one straight cut of a knife?

ANS. Join the centers of the original and the removed rectangle. It works for cuboids too! BTW, I have been getting many questions asking why a horizontal slice across the middle will not do. Please note the "any size or orientation" in the question! Don't get boxed in by the way you cut your birthday cake :) Think out of the box.

2. There are 3 baskets. one of them have apples, one has oranges only and the other has mixture of apples and oranges. The labels on their baskets always lie. (i.e. if the label says oranges, you are sure that it doesn't have oranges only,it could be a mixture) The task is to pick one basket and pick only one fruit from it and then correctly label all the three baskets.

HINT. There are only two combinations of distributions in which ALL the baskets have wrong labels. By picking a fruit from the one labeled MIXTURE, it is possible to tell what the other two baskets have.

3. You have 8 balls. One of them is defective and weighs less than others. You have a balance to measure balls against each other. In 2 weighings how do you find the defective one?

4. Why is a manhole cover round?

HINT. The diagonal of a square hole is larger than the side of a cover!

Alternate answers: 1. Round covers can be transported by one person, because they can be rolled on their edge. 2. A round cover doesn't need to be rotated to fit over a hole.

5. How many cars are there in the USA?

6. You've got someone working for you for seven days and a gold bar to pay them. The gold bar is segmented into seven connected pieces. You must give them a piece of gold at the end of every day. If you are only allowed to make two breaks in the gold bar, how do you pay your worker?

7. One train leaves Los Angeles at 15mph heading for New York. Another train leaves from New York at 20mph heading for Los Angeles on the same track. If a bird, flying at 25mph, leaves from Los Angeles at the same time as the train and flies back and forth between the two trains until they collide, how far will the bird have traveled?

HINT. Think relative speed of the trains.

8. You have two jars, 50 red marbles and 50 blue marbles. A jar will be picked at random, and then a marble will be picked from the jar. Placing all of the marbles in the jars, how can you maximize the chances of a red marble being picked? What are the exact odds of getting a red marble using your scheme?

9. Imagine you are standing in front of a mirror, facing it. Raise your left hand. Raise your right hand. Look at your reflection. When you raise your left hand your reflection raises what appears to be his right hand. But when you tilt your head up, your reflection does too, and does not appear to tilt his/her head down. Why is it that the mirror appears to reverse left and right, but not up and down?

10. You have 5 jars of pills. Each pill weighs 10 gram, except for contaminated pills contained in one jar, where each pill weighs 9 gm. Given a scale, how could you tell which jar had the contaminated pills in just one measurement?

ANS. 1. Mark the jars with numbers 1, 2, 3, 4, and 5.
2. Take 1 pill from jar 1, take 2 pills from jar 2, take 3 pills from jar 3, take 4 pills from jar 4 and take 5 pills from jar 5.
3. Put all of them on the scale at once and take the measurement.
4. Now, subtract the measurement from 150 ( 1*10 + 2*10 + 3*10 + 4*10 + 5*10)
5. The result will give you the jar number which has contaminated pill.

11. If you had an infinite supply of water and a 5 quart and 3 quart pail, how would you measure exactly 4 quarts?

12. You have a bucket of jelly beans. Some are red, some are blue, and some green. With your eyes closed, pick out 2 of a like color. How many do you have to grab to be sure you have 2 of the same?

13. Which way should the key turn in a car door to unlock it?

14. If you could remove any of the 50 states, which state would it be and why?

15. There are four dogs/ants/people at four corners of a square of unit distance. At the same instant all of them start running with unit speed towards the person on their clockwise direction and will always run towards that target. How long does it take for them to meet and where?

HINT. They will meet in the center and the distance covered by them is independent of the path they actually take (a spiral).

16. (from Tara Hovel) A helicopter drops two trains, each on a parachute, onto a straight infinite railway line. There is an undefined distance between the two trains. Each faces the same direction, and upon landing, the parachute attached to each train falls to the ground next to the train and detaches. Each train has a microchip that controls its motion. The chips are identical. There is no way for the trains to know where they are. You need to write the code in the chip to make the trains bump into each other. Each line of code takes a single clock cycle to execute.
You can use the following commands (and only these);
MF - moves the train forward
MB - moves the train backward
IF (P) - conditional that's satisfied if the train is next to a parachute. There is no "then" to this IF statement.
GOTO

ANS.
A: MF
IF (P)
GOTO B
GOTO A
-----
B: MF
GOTO B
Explanation: The first line simply gets them off the parachutes. You need to get the trains off their parachutes so the back train can find the front train's parachute, creating a special condition that will allow it to break out of the code they both have to follow initially. They both loop through A: until the back train finds the front train's parachute, at which point it goes to B: and gets stuck in that loop. The front train still hasn't found a parachute, so it keeps in the A loop. Because each line of code takes a "clock cycle" to execute, it takes longer to execute the A loop than the B loop, therefore the back train (running in the B loop) will catch up to the front train.

Personality

It is best to read some website or a book for questions like these.

1. Tell me the courses you liked and why did you like them.

2. Give an instance in your life in which you were faced with a problem and you tackled it successfully.

3. What is your ideal working environment.

4. Why do you think you are smart.

5. Questions on the projects listed on the Resume.

6. Do you want to know any thing about the company.( Try to ask some relevant and interesting question).

7. How long do you want to stay in USA and why (I guess non-citizens get this)?

8. What is your geographical preference?

9. What are your expectations from the job.


Algorithms and Programming

1. Given a rectangular (cuboidal for the puritans) cake with a rectangular piece removed (any size or orientation), how would you cut the remainder of the cake into two equal halves with one straight cut of a knife ?

2. You're given an array containing both positive and negative integers and required to find the sub-array with the largest sum (O(N) a la KBL). Write a routine in C for the above.

3. Given an array of size N in which every number is between 1 and N, determine if there are any duplicates in it. You are allowed to destroy the array if you like. [ I ended up giving about 4 or 5 different solutions for this, each supposedly better than the others ].

4. Write a routine to draw a circle (x ** 2 + y ** 2 = r ** 2) without making use of any floating point computations at all. [ This one had me stuck for quite some time and I first gave a solution that did have floating point computations ].

5. Given only putchar (no sprintf, itoa, etc.) write a routine putlong that prints out an unsigned long in decimal. [ I gave the obvious solution of taking % 10 and / 10, which gives us the decimal value in reverse order. This requires an array since we need to print it out in the correct order. The interviewer wasn't too pleased and asked me to give a solution which didn't need the array ].

6. Give a one-line C expression to test whether a number is a power of 2. [No loops allowed - it's a simple test.]

7. Given an array of characters which form a sentence of words, give an efficient algorithm to reverse the order of the words (not characters) in it.

8. How many points are there on the globe where by walking one mile south, one mile east and one mile north you reach the place where you started.

9. Give a very good method to count the number of ones in a "n" (e.g. 32) bit number.

ANS. Given below are simple solutions, find a solution that does it in log (n) steps.

Iterative

function iterativecount (unsigned int n)
begin
int count=0;
while (n)
begin
count += n & 0x1 ;
n >>= 1;
end
return count;
end

Sparse Count

function sparsecount (unsigned int n)
begin
int count=0;
while (n)
begin
count++;
n &= (n-1);
end
return count ;
end

10. What are the different ways to implement a condition where the value of x can be either a 0 or a 1. Apparently the if then else solution has a jump when written out in assembly. if (x == 0) y=a else y=b There is a logical, arithmetic and a data structure solution to the above problem.

11. Reverse a linked list.

12. Insert in a sorted list

13. In a X's and 0's game (i.e. TIC TAC TOE) if you write a program for this give a fast way to generate the moves by the computer. I mean this should be the fastest way possible.

The answer is that you need to store all possible configurations of the board and the move that is associated with that. Then it boils down to just accessing the right element and getting the corresponding move for it. Do some analysis and do some more optimization in storage since otherwise it becomes infeasible to get the required storage in a DOS machine.

14. I was given two lines of assembly code which found the absolute value of a number stored in two's complement form. I had to recognize what the code was doing. Pretty simple if you know some assembly and some fundaes on number representation.

15. Give a fast way to multiply a number by 7.

16. How would go about finding out where to find a book in a library. (You don't know how exactly the books are organized beforehand).

17. Linked list manipulation.

18. Tradeoff between time spent in testing a product and getting into the market first.

19. What to test for given that there isn't enough time to test everything you want to.

20. First some definitions for this problem: a) An ASCII character is one byte long and the most significant bit in the byte is always '0'. b) A Kanji character is two bytes long. The only characteristic of a Kanji character is that in its first byte the most significant bit is '1'.

Now you are given an array of a characters (both ASCII and Kanji) and, an index into the array. The index points to the start of some character. Now you need to write a function to do a backspace (i.e. delete the character before the given index).

21. Delete an element from a doubly linked list.

22. Write a function to find the depth of a binary tree.

23. Given two strings S1 and S2. Delete from S2 all those characters which occur in S1 also and finally create a clean S2 with the relevant characters deleted.

24. Assuming that locks are the only reason due to which deadlocks can occur in a system. What would be a foolproof method of avoiding deadlocks in the system.

25. Reverse a linked list.

Ans: Possible answers -

iterative loop
curr->next = prev;
prev = curr;
curr = next;
next = curr->next
endloop

recursive reverse(ptr)
if (ptr->next == NULL)
return ptr;
temp = reverse(ptr->next);
temp->next = ptr;
return ptr;
end

26. Write a small lexical analyzer - interviewer gave tokens. expressions like "a*b" etc.

27. Besides communication cost, what is the other source of inefficiency in RPC? (answer : context switches, excessive buffer copying). How can you optimize the communication? (ans : communicate through shared memory on same machine, bypassing the kernel _ A Univ. of Wash. thesis)

28. Write a routine that prints out a 2-D array in spiral order!

29. How is the readers-writers problem solved? - using semaphores/ada .. etc.

30. Ways of optimizing symbol table storage in compilers.

31. A walk-through through the symbol table functions, lookup() implementation etc. - The interviewer was on the Microsoft C team.

32. A version of the "There are three persons X Y Z, one of which always lies".. etc..

33. There are 3 ants at 3 corners of a triangle, they randomly start moving towards another corner.. what is the probability that they don't collide.

34. Write an efficient algorithm and C code to shuffle a pack of cards.. this one was a feedback process until we came up with one with no extra storage.

35. The if (x == 0) y = 0 etc..

36. Some more bitwise optimization at assembly level

37. Some general questions on Lex, Yacc etc.

38. Given an array t[100] which contains numbers between 1..99. Return the duplicated value. Try both O(n) and O(n-square).

39. Given an array of characters. How would you reverse it. ? How would you reverse it without using indexing in the array.

40. Given a sequence of characters. How will you convert the lower case characters to upper case characters. ( Try using bit vector - solutions given in the C lib -typec.h)

41. Fundamentals of RPC.

42. Given a linked list which is sorted. How will u insert in sorted way.

43. Given a linked list How will you reverse it.

44. Give a good data structure for having n queues ( n not fixed) in a finite memory segment. You can have some data-structure separate for each queue. Try to use at least 90% of the memory space.

45. Do a breadth first traversal of a tree.

46. Write code for reversing a linked list.

47. Write, efficient code for extracting unique elements from a sorted list of array. e.g. (1, 1, 3, 3, 3, 5, 5, 5, 9, 9, 9, 9) -> (1, 3, 5, 9).

48. Given an array of integers, find the contiguous sub-array with the largest sum.

ANS. Can be done in O(n) time and O(1) extra space. Scan array from 1 to n. Remember the best sub-array seen so far and the best sub-array ending in i.

49. Given an array of length N containing integers between 1 and N, determine if it contains any duplicates.

ANS. [Is there an O(n) time solution that uses only O(1) extra space and does not destroy the original array?]

50. Sort an array of size n containing integers between 1 and K, given a temporary scratch integer array of size K.

ANS. Compute cumulative counts of integers in the auxiliary array. Now scan the original array, rotating cycles! [Can someone word this more nicely?]

* 51. An array of size k contains integers between 1 and n. You are given an additional scratch array of size n. Compress the original array by removing duplicates in it. What if k <<>

ANS. Can be done in O(k) time i.e. without initializing the auxiliary array!

52. An array of integers. The sum of the array is known not to overflow an integer. Compute the sum. What if we know that integers are in 2's complement form?

ANS. If numbers are in 2's complement, an ordinary looking loop like for(i=total=0;i<>

53. An array of characters. Reverse the order of words in it.

ANS. Write a routine to reverse a character array. Now call it for the given array and for each word in it.

* 54. An array of integers of size n. Generate a random permutation of the array, given a function rand_n() that returns an integer between 1 and n, both inclusive, with equal probability. What is the expected time of your algorithm?

ANS. "Expected time" should ring a bell. To compute a random permutation, use the standard algorithm of scanning array from n downto 1, swapping i-th element with a uniformly random element <= i-th. To compute a uniformly random integer between 1 and k (k <>

55. An array of pointers to (very long) strings. Find pointers to the (lexicographically) smallest and largest strings.

ANS. Scan array in pairs. Remember largest-so-far and smallest-so-far. Compare the larger of the two strings in the current pair with largest-so-far to update it. And the smaller of the current pair with the smallest-so-far to update it. For a total of <= 3n/2 strcmp() calls. That's also the lower bound.

56. Write a program to remove duplicates from a sorted array.

ANS. int remove_duplicates(int * p, int size)
{
int current, insert = 1;
for (current=1; current < size; current++)
if (p[current] != p[insert-1])
{
p[insert] = p[current];
current++;
insert++;
} else
current++;

return insert;

}

57. C++ ( what is virtual function ? what happens if an error occurs in constructor or destructor. Discussion on error handling, templates, unique features of C++. What is different in C++, ( compare with unix).

58. Given a list of numbers ( fixed list) Now given any other list, how can you efficiently find out if there is any element in the second list that is an element of the first list (fixed list).

59. Given 3 lines of assembly code : find it is doing. IT was to find absolute value.

60. If you are on a boat and you throw out a suitcase, Will the level of water increase.

61. Print an integer using only putchar. Try doing it without using extra storage.

62. Write C code for (a) deleting an element from a linked list (b) traversing a linked list

63. What are various problems unique to distributed databases

64. Declare a void pointer ANS. void *ptr;

65. Make the pointer aligned to a 4 byte boundary in a efficient manner ANS. Assign the pointer to a long number and the number with 11...1100 add 4 to the number

66. What is a far pointer (in DOS)

67. What is a balanced tree

68. Given a linked list with the following property node2 is left child of node1, if node2 <>

 O P
|
|
O A
|
|
O B
|
|
O C

How do you convert the above linked list to the form without disturbing the property. Write C code for that.

   O P
|
|
O B
/ / / O ? O ?

determine where do A and C go

69. Describe the file system layout in the UNIX OS

ANS. describe boot block, super block, inodes and data layout

70. In UNIX, are the files allocated contiguous blocks of data

ANS. no, they might be fragmented

How is the fragmented data kept track of

ANS. Describe the direct blocks and indirect blocks in UNIX file system

71. Write an efficient C code for 'tr' program. 'tr' has two command line arguments. They both are strings of same length. tr reads an input file, replaces each character in the first string with the corresponding character in the second string. eg. 'tr abc xyz' replaces all 'a's by 'x's, 'b's by 'y's and so on. ANS.
a) have an array of length 26.
put 'x' in array element corr to 'a'
put 'y' in array element corr to 'b'
put 'z' in array element corr to 'c'
put 'd' in array element corr to 'd'
put 'e' in array element corr to 'e'
and so on.

the code
while (!eof)
{
c = getc();
putc(array[c - 'a']);
}

72. what is disk interleaving

73. why is disk interleaving adopted

74. given a new disk, how do you determine which interleaving is the best a) give 1000 read operations with each kind of interleaving determine the best interleaving from the statistics

75. draw the graph with performance on one axis and 'n' on another, where 'n' in the 'n' in n-way disk interleaving. (a tricky question, should be answered carefully)

76. I was a c++ code and was asked to find out the bug in that. The bug was that he declared an object locally in a function and tried to return the pointer to that object. Since the object is local to the function, it no more exists after returning from the function. The pointer, therefore, is invalid outside.

77. A real life problem - A square picture is cut into 16 squares and they are shuffled. Write a program to rearrange the 16 squares to get the original big square.

78.
int *a;
char *c;
*(a) = 20;
*c = *a;
printf("%c",*c);

what is the output?

79. Write a program to find whether a given m/c is big-endian or little-endian!

80. What is a volatile variable?

81. What is the scope of a static function in C ?

82. What is the difference between "malloc" and "calloc"?

83. struct n { int data; struct n* next}node;
node *c,*t;
c->data = 10;
t->next = null;
*c = *t;
what is the effect of the last statement?

84. If you're familiar with the ? operator x ? y : z
you want to implement that in a function: int cond(int x, int y, int z); using only ~, !, ^, &, +, |, <<, >> no if statements, or loops or anything else, just those operators, and the function should correctly return y or z based on the value of x. You may use constants, but only 8 bit constants. You can cast all you want. You're not supposed to use extra variables, but in the end, it won't really matter, using vars just makes things cleaner. You should be able to reduce your solution to a single line in the end though that requires no extra vars.

85. You have an abstract computer, so just forget everything you know about computers, this one only does what I'm about to tell you it does. You can use as many variables as you need, there are no negative numbers, all numbers are integers. You do not know the size of the integers, they could be infinitely large, so you can't count on truncating at any point. There are NO comparisons allowed, no if statements or anything like that. There are only four operations you can do on a variable.
1) You can set a variable to 0.
2) You can set a variable = another variable.
3) You can increment a variable (only by 1), and it's a post increment.
4) You can loop. So, if you were to say loop(v1) and v1 = 10, your loop would execute 10 times, but the value in v1 wouldn't change so the first line in the loop can change value of v1 without changing the number of times you loop.
You need to do 3 things.
1) Write a function that decrements by 1.
2) Write a function that subtracts one variable from another.
3) Write a function that divides one variable by another.
4) See if you can implement all 3 using at most 4 variables. Meaning, you're not making function calls now, you're making macros. And at most you can have 4 variables. The restriction really only applies to divide, the other 2 are easy to do with 4 vars or less. Division on the other hand is dependent on the other 2 functions, so, if subtract requires 3 variables, then divide only has 1 variable left unchanged after a call to subtract. Basically, just make your function calls to decrement and subtract so you pass your vars in by reference, and you can't declare any new variables in a function, what you pass in is all it gets.

Linked lists

* 86. Under what circumstances can one delete an element from a singly linked list in constant time?

ANS. If the list is circular and there are no references to the nodes in the list from anywhere else! Just copy the contents of the next node and delete the next node. If the list is not circular, we can delete any but the last node using this idea. In that case, mark the last node as dummy!

* 87. Given a singly linked list, determine whether it contains a loop or not.

ANS. (a) Start reversing the list. If you reach the head, gotcha! there is a loop!
But this changes the list. So, reverse the list again.
(b) Maintain two pointers, initially pointing to the head. Advance one of them one node at a time. And the other one, two nodes at a time. If the latter overtakes the former at any time, there is a loop!

          p1 = p2 = head;

do {
p1 = p1->next;
p2 = p2->next->next;
} while (p1 != p2);

88. Given a singly linked list, print out its contents in reverse order. Can you do it without using any extra space?

ANS. Start reversing the list. Do this again, printing the contents.

89. Given a binary tree with nodes, print out the values in pre-order/in-order/post-order without using any extra space.

90. Reverse a singly linked list recursively. The function prototype is node * reverse (node *) ;

ANS.

    node * reverse (node * n)
{
node * m ;

if (! (n && n -> next))
return n ;

m = reverse (n -> next) ;
n -> next -> next = n ;
n -> next = NULL ;
return m ;
}

91. Given a singly linked list, find the middle of the list.

HINT. Use the single and double pointer jumping. Maintain two pointers, initially pointing to the head. Advance one of them one node at a time. And the other one, two nodes at a time. When the double reaches the end, the single is in the middle. This is not asymptotically faster but seems to take less steps than going through the list twice.

Bit-manipulation

92. Reverse the bits of an unsigned integer.

ANS.

    #define reverse(x)                                           (x=x>>16|(0x0000ffff&x)<<16,                          x=(0xff00ff00&x)>>8|(0x00ff00ff&x)<<8,               x=(0xf0f0f0f0&x)>>4|(0x0f0f0f0f&x)<<4,               x=(0xcccccccc&x)>>2|(0x33333333&x)<<2,               x=(0xaaaaaaaa&x)>>1|(0x55555555&x)<<1)

* 93. Compute the number of ones in an unsigned integer.

ANS.

   #define count_ones(x)                                     (x=(0xaaaaaaaa&x)>>1+(0x55555555&x),               x=(0xcccccccc&x)>>2+(0x33333333&x),               x=(0xf0f0f0f0&x)>>4+(0x0f0f0f0f&x),               x=(0xff00ff00&x)>>8+(0x00ff00ff&x),               x=x>>16+(0x0000ffff&x))

94. Compute the discrete log of an unsigned integer.

ANS.

#define discrete_log(h) (h=(h>>1)|(h>>2), h|=(h>>2), h|=(h>>4), h|=(h>>8), h|=(h>>16), h=(0xaaaaaaaa&h)>>1+(0x55555555&h), h=(0xcccccccc&h)>>2+(0x33333333&h), h=(0xf0f0f0f0&h)>>4+(0x0f0f0f0f&h), h=(0xff00ff00&h)>>8+(0x00ff00ff&h), h=(h>>16)+(0x0000ffff&h))
If I understand it right, log2(2) =1, log2(3)=1, log2(4)=2..... But this macro does not work out log2(0) which does not exist! How do you think it should be handled?

* 95. How do we test most simply if an unsigned integer is a power of two?

ANS. #define power_of_two(x) \ ((x)&&(~(x&(x-1))))

96. Set the highest significant bit of an unsigned integer to zero.

ANS. (from Denis Zabavchik) Set the highest significant bit of an unsigned integer to zero
#define zero_most_significant(h) (h&=(h>>1)|(h>>2), h|=(h>>2), h|=(h>>4), h|=(h>>8), h|=(h>>16))

97. Let f(k) = y where k is the y-th number in the increasing sequence of non-negative integers with the same number of ones in its binary representation as y, e.g. f(0) = 1, f(1) = 1, f(2) = 2, f(3) = 1, f(4) = 3, f(5) = 2, f(6) = 3 and so on. Given k >= 0, compute f(k).

Others

98. A character set has 1 and 2 byte characters. One byte characters have 0 as the first bit. You just keep accumulating the characters in a buffer. Suppose at some point the user types a backspace, how can you remove the character efficiently. (Note: You cant store the last character typed because the user can type in arbitrarily many backspaces)

99. What is the simples way to check if the sum of two unsigned integers has resulted in an overflow.

100. How do you represent an n-ary tree? Write a program to print the nodes of such a tree in breadth first order.

101. Write the 'tr' program of UNIX. Invoked as

tr -str1 -str2. It reads stdin and prints it out to stdout, replacing every occurance of str1[i] with str2[i].

e.g. tr -abc -xyz
to be and not to be <- input
to ye xnd not to ye <- output


Networks and Security

1. How do you use RSA for both authentication and secrecy?

2. What is ARP and how does it work?

3. What's the difference between a switch and a router?

4. Name some routing protocols? (RIP,OSPF etc..)

5. How do you do authentication with message digest(MD5)? (Usually MD is used for finding tampering of data)

6. How do you implement a packet filter that distinguishes following cases and selects first case and rejects second case.

i) A host inside the corporate n/w makes a ftp request to outside host and the outside host sends reply.

ii) A host outside the network sends a ftp request to host inside. for the packet filter in both cases the source and destination fields will look the same.

7. How does traceroute work? Now how does traceroute make sure that the packet follows the same path that a previous (with ttl - 1) probe packet went in?

8. Explain Kerberos Protocol ?

9. What are digital signatures and smart cards?

10. Difference between discretionary access control and mandatory access control?

Java

1. How do you find the size of a java object (not the primitive type) ?

ANS. type cast it to string and find its s.length()

2. Why is multiple inheritance not provided in Java?

3. Thread t = new Thread(); t.start(); t = null; now what will happen to the created thread?

4. How is garbage collection done in java?

5. How do you write a "ping" routine in java?

6. What are the security restrictions on applets?

Graphics

1. Write a function to check if two rectangles defined as below overlap or not. struct rect { int top, bot, left, right; } r1, r2;

2. Write a SetPixel(x, y) function, given a pointer to the bitmap. Each pixel is represented by 1 bit. There are 640 pixels per row. In each byte, while the bits are numbered right to left, pixels are numbered left to right. Avoid multiplications and divisions to improve performance.

Databases

* 1. You, a designer want to measure disk traffic i.e. get a histogram showing the relative frequency of I/O/second for each disk block. The buffer pool has b buffers and uses LRU replacement policy. The disk block size and buffer pool block sizes are the same. You are given a routine int lru_block_in_position (int i) which returns the block_id of the block in the i-th position in the list of blocks managed by LRU. Assume position 0 is the hottest. You can repeatedly call this routine. How would you get the histogram you desire?

Hints and Answers

1. Simply do histogram [lru_block_in_position (b-1)] ++ at frequent intervals... The sampling frequency should be close to the disk I/O rate. It can be adjusted by remembering the last block seen in position b. If same, decrease frequency; if different, increase, with exponential decay etc. And of course, take care of overflows in the histogram.

Semaphores

1. Implement a multiple-reader-single-writer lock given a compare-and-swap instruction. Readers cannot overtake waiting writers.



Computer Architecture

1. Explain what is DMA?
2. What is pipelining?
3. What are superscalar machines and vliw machines?
4. What is cache?
5. What is cache coherency and how is it eliminated?
6. What is write back and write through caches?
7. What are different pipelining hazards and how are they eliminated.
8. What are different stages of a pipe?
9. Explain more about branch prediction in controlling the control hazards
10. Give examples of data hazards with pseudo codes.
11. How do you calculate the number of sets given its way and size in a cache?
12. How is a block found in a cache?
13. Scoreboard analysis.
14. What is miss penalty and give your own ideas to eliminate it.
15. How do you improve the cache performance.
16. Different addressing modes.
17. Computer arithmetic with two's complements.
18. About hardware and software interrupts.
19. What is bus contention and how do you eliminate it.
20. What is aliasing?
21) What is the difference between a latch and a flip flop?
22) What is the race around condition? How can it be overcome?
23) What is the purpose of cache? How is it used?
24) What are the types of memory management?
  1. What are the basic functions of an operating system?
  2. Explain briefly about, processor, assembler, compiler, loader, linker and the functions executed by them.
  3. What are the difference phases of software development? Explain briefly?
  4. Differentiate between RAM and ROM?
  5. What is DRAM? In which form does it store data?
  6. What is cache memory?
  7. What is hard disk and what is its purpose?
  8. Differentiate between Complier and Interpreter?
  9. What are the different tasks of Lexical analysis?
  10. What are the different functions of Syntax phase, Scheduler?
  11. What are the main difference between Micro-Controller and Micro- Processor?
  12. Describe different job scheduling in operating systems.
  13. What is a Real-Time System ?
  14. What is the difference between Hard and Soft real-time systems ?
  15. What is a mission critical system ?
  16. What is the important aspect of a real-time system ?
  17. If two processes which shares same system memory and system clock in a distributed system, What is it called?
  18. What is the state of the processor, when a process is waiting for some event to occur?
  19. What do you mean by deadlock?
  20. Explain the difference between microkernel and macro kernel.
  21. Give an example of microkernel.
  22. When would you choose bottom up methodology?
  23. When would you choose top down methodology?
  24. Write a small dc shell script to find number of FF in the design.
  25. Why paging is used ?
  26. Which is the best page replacement algorithm and Why? How much time is spent usually in each phases and why?
  27. Difference between Primary storage and secondary storage?
  28. What is multi tasking, multi programming, multi threading?
  29. Difference between multi threading and multi tasking?
  30. Define Demand paging, page faults, replacement algorithms, thrashing,.
  31. Explain about paged segmentation and segment paging
  32. While running DOS on a PC, which command would be used to duplicate the entire diskette?
  33. What is MUTEX ?
  34. What isthe difference between a 'thread' and a 'process'?
  35. What is INODE?
  36. Explain the working of Virtual Memory.
  37. How does Windows NT supports Multitasking?
  38. Explain the Unix Kernel.
  39. What is Concurrency? Expain with example Deadlock and Starvation.
  40. What are your solution strategies for "Dining Philosophers Problem" ?
  41. Explain Memory Partitioning, Paging, Segmentation.
  42. Explain Scheduling.
  43. Operating System Security.
  44. What is Semaphore?
  45. Explain the following file systems : NTFS, Macintosh(HPFS), FAT .
  46. What are the different process states?
  47. What is Marshalling?
  48. Define and explain COM?
  49. Difference - Loading and Linking ?
  1. What is a data structure?
  2. What does abstract data type means?
  3. Evaluate the following prefix expression " ++ 26 + - 1324" (Similar types can be asked)
  4. Convert the following infix expression to post fix notation ((a+2)*(b+4)) -1 (Similar types can be asked)
  5. How is it possible to insert different type of elements in stack?
  6. Stack can be described as a pointer. Explain.
  7. Write a Binary Search program
  8. Write programs for Bubble Sort, Quick sort
  9. Explain about the types of linked lists
  10. How would you sort a linked list?
  11. Write the programs for Linked List (Insertion and Deletion) operations
  12. What data structure would you mostly likely see in a non recursive implementation of a recursive algorithm?
  13. What do you mean by Base case, Recursive case, Binding Time, Run-Time Stack and Tail Recursion?
  14. Explain quick sort and merge sort algorithms and derive the time-constraint relation for these.
  15. Explain binary searching, Fibinocci search.
  16. What is the maximum total number of nodes in a tree that has N levels? Note that the root is level (zero)
  17. How many different binary trees and binary search trees can be made from three nodes that contain the key values 1, 2 & 3?
  18. A list is ordered from smaller to largest when a sort is called. Which sort would take the longest time to execute?
  19. A list is ordered from smaller to largest when a sort is called. Which sort would take the shortest time to execute?
  20. When will you sort an array of pointers to list elements, rather than sorting the elements themselves?
  21. The element being searched for is not found in an array of 100 elements. What is the average number of comparisons needed in a sequential search to determine that the element is not there, if the elements are completely unordered?
  22. What is the average number of comparisons needed in a sequential search to determine the position of an element in an array of 100 elements, if the elements are ordered from largest to smallest?
  23. Which sort show the best average behavior?
  24. What is the average number of comparisons in a sequential search?
  25. Which data structure is needed to convert infix notations to post fix notations?
  26. What do you mean by:
    • Syntax Error
    • Logical Error
    • Runtime Error

How can you correct these errors?

  1. In which data structure, elements can be added or removed at either end, but not in the middle?
  2. How will inorder, preorder and postorder traversals print the elements of a tree?
  3. Parenthesis are never needed in prefix or postfix expressions. Why?
  4. Which one is faster? A binary search of an orderd set of elements in an array or a sequential search of the elements.