OS Data Structures Interview Questions And Answers

printf,scanf,getch,getchar,getche,kbhit etc

Used mainly to represent elements in a dynamic environment where it is added on an ad-hoc basis.
Especially in the cases where the total number of elements in the list cannot be pre-decided, linked lists are used. This does not lead to space insufficiency or space wastage as in case of arrays.
For eg. The no. of terms in a order-n polynomial varies greatly, using an array to store the co-efficients is an inefficient methods. If the array size is declared 100, a quadratic equation will use just 3 index and the rest 99 will be wasted. While for a sine or cosine series (from x to infinity) an overflow error might occur..!

void bubble(int x[],int n)
{
int hold,j,pass;
int switched=true;
for(pass=0;pass<n-1&&switched=true;pass++){
switched=false;
for(j=0;j<n-pass-1;j++)
if(x[j]>x[j+1]){
switched=true;
hold=x[j];
x[j]=x[j+1];
x[j+1]=hold;
}
}
}

Keeping track of nested invocation calls in a procedural
programming language, such as C/C++.
Each function call results in a new entry being placed into
the program run-time stack. This new
entry contains memory space for local variables (which can
grow dynamically) and for a return
pointer to the instruction in the function that invoked the
current function (caller/callee). As
functions terminate, their stack entry is "popped out," with
the return values written to the proper
location in the caller.
Since nested procedural/ function invocation levels are
entered and exited in LIFO order, a stack
is the most appropriate data structure to handle this
functionality.
Evaluating arithmetic expressions.
Stacks can be used to parse arithmetic expressions and
evaluate them efficiently, as we shall
see as part of this assignment.
To eliminate the need for direct implementation of recursion.
As recursive function calls require a lot of overhead, it is
often the case that recursive algorithms
are "unrolled" into non-recursive ones. Since recursive
calls are entered/exited in LIFO order the
use of stacks to mimic recursion is a natural choice.

Tree always takes o(log n) time because tree has height is
(log n).

number of possible tree = (2 power n) - n.
for example:
A tree contain three node.
so n=3.
possible tree = 8 - 3 = 5.

we can use the binary search algorithm for this problem because this searching algorithm has O(log n) performance in both worse and average case.

It's all about branching factor. Because of the way B+-Trees store records (called "satellite information") at the leaf level of the tree, they maximize the branching factor of the internal nodes. High branching factor allows for a tree of lower height. Lower tree height allows for less disk I/O. Less disk I/O theoretically means better performance
In a B- tree you can store both keys and data in the internal/leaf nodes. But in a B+ tree you have to store the data in the leaf nodes only.
A B+ - Tree is in the form of a balanced tree in which every path from the root of the tree to a leaf of the tree is the same length.
Each nonleaf node in the tree has between [n/2] and n children, where n is fixed.
B+ - Trees are good for searches, but cause some overhead issues in wasted space.

A red black tree is a binary tree where
1. every node has color.
2. root node is always black
3. the child of a black node is either black or red
4. both the child nodes of every red node must be black
5. all the leaves must be black

enum is not an basic data type like int,float and all it is
a user defined data type, and printf function works only
with basic data type, we 've overload printf function to
make it work for user defined data types :)

Compile time polymorphism(Static polymorphism) means
basically those language structure which will cause the
compiler to produce code at the compile-time. That is, the
compiler is well aware that what code is to be generated at
the compile-time itself: Ex: overloading of operators,
functions.

Run time Polymorphism(Dynamic Polymorphism)means that the
compiler is unaware what code is to be generated so it binds
the possible code and let the program decide it at the
run-time itself.Ex: the virtualness of a class member or the
entire class itself.

Rael world example fo polymorphism can be start machnism of
bike, inwhich u wil hav same method start() but it may be
either by kick start or button start.
N example for encapsulation can be a stack or queue doesn't
matter how it is implented internally with linked list or array

An AVL tree is a self-balancing binary search tree, and it
was the first such data structure to be invented.In an AVL
tree, the heights of the two child subtrees of any node
differ by at most one. Lookup, insertion, and deletion all
take O(log n) time in both the average and worst cases,
where n is the number of nodes in the tree prior to the
operation. Insertions and deletions may require the tree to
be rebalanced by one or more tree rotations.

In linear search each element in the array should be checked
until the required element got searched whereas in binary
search array is divided into two and required element is
searched