Sunday, February 17, 2008

Data Structures Interview Questions

What is the easiest sorting method to use?
The answer is the standard library function qsort(). It's the easiest sort by far for several reasons:
It is already written.
It is already debugged.
It has been optimized as much as possible (usually).
Void qsort(void *buf, size_t num, size_t size, int (*comp)(const void *ele1, const void *ele2));

What is the bucket size, when the overlapping and collision occur at same time?
One. If there is only one entry possible in the bucket, when the collision occurs, there is no way to accommodate the colliding value. This results in the overlapping of values.

In an AVL tree, at what condition the balancing is to be done?
If the pivotal value (or the Height factor) is greater than 1 or less than 1.

Minimum number of queues needed to implement the priority queue?
Two. One queue is used for actual storing of data and another for storing priorities.

How many different trees are possible with 10 nodes ?
1014 - For example, consider a tree with 3 nodes(n=3), it will have the maximum combination of 5 different (ie, 23 - 3 =? 5) trees.

What is a node class?
A node class is a class that, relies on the base class for services and  implementation, provides a wider interface to users than its base class, relies primarily on virtual functions in its public interface depends on all its direct and indirect base class can be understood only in the context of the base class can be used as base for further derivation
can be used to create objects. A node class is a class that has added new services or functionality beyond the services inherited from its base class.

When can you tell that a memory leak will occur?
A memory leak occurs when a program loses the ability to free a block of dynamically allocated memory.

What is placement new?
When you want to call a constructor directly, you use the placement new. Sometimes you have some raw memory that's already been allocated, and you need to construct an object in the memory you have. Operator new's special version placement new allows you to do it.
class Widget
{
public :
Widget(int widgetsize);

Widget* Construct_widget_int_buffer(void *buffer,int widgetsize)
{
return new(buffer) Widget(widgetsize);
}
};
This function returns a pointer to a Widget object that's constructed within the buffer passed to the function. Such a function might be useful for applications using shared memory or memory-mapped I/O, because objects in such applications must be placed at specific addresses or in memory allocated by special routines.