SDE - 1

Factorial of a number is basically the product of all integers smaller than or equal to that number. 
Iterative solution :
Run a for loop from 1 to n and take the product of all the numbers. 
The final product will be the desired answer.
Time Complexity : O(n)
Space Complexity : O(1)
Recursive solution :
The following recursive formula can be used for recursive solution :
n! = n * (n-1)!
n! = 1 if n = 0 or n = 1
Time Complexity : O(n)
Space Complexity : O(n)

Binary search is an efficient algorithm for finding an item from a sorted list of items. It works by repeatedly dividing in half the portion of the list that could contain the item, until you've narrowed down the possible locations to just one. 
Pseudocode :
binarySearch(low,high,key)
{
while(low<=high)
{
mid=(low+high)/2
if(a[mid]key)
{
high=mid-1;
}
else
{
return mid;
}
}
return -1; //key not found
}

Semaphore is a non-negative variable shared between threads. It is a signaling mechanism, and a thread that is waiting on a semaphore can be signaled by another thread. It uses two atomic operations, 1)wait, and 2) signal for the process synchronization. There are two types of semaphore :Counting and binary semaphores

1.In DBMS, the data is stored as a file, while in RDBMS, the information is stored in tables.
2.DBMS can only be used by one single user, whereas multiple users can use RDMBS.
3.Client-server side interaction and architecture are only supported in RDBMS, whereas DBMS does not support client-server side interaction.
4.DBMS is lighter in its hardware and software requirements than RDMBS.

Bubble sort is a sorting algorithm that works on the repeatedly swapping of adjacent elements until they are not in the intended order. Algorithm :
BubbleSort(arr) 
for all array elements 
if arr[i] > arr[i+1] 
swap(arr[i], arr[i+1]) 
return arr

Time Complexity : O(n^2)

Merge sort works on the principle of Divide and Conquer. Merge sort repeatedly breaks down a list into several sub lists until each sub list consists of a single element and merging those sub lists in a manner that results into a sorted list.
Algorithm :
MergeSort(arr[], l, r)
If r > l
1. Find the middle point to divide the array into two halves: 
middle m = l+ (r-l)/2
2. Call mergeSort for first half: 
Call mergeSort(arr, l, m)
3. Call mergeSort for second half:
Call mergeSort(arr, m+1, r)
4. Merge the two halves sorted in step 2 and 3:
Call merge(arr, l, m, r)
The time complexity of merge sort is O(nlogn) and auxiliary space is O(n).

SELECT E.empid, E.empname, E.dept, F.salary
FROM Table1 E, Table2 F 
where E.empid == F.empid and ( select count(*) from F where salary > F.salary ) < 5order by salary desc;

Normalization is the process of reorganizing data in a database so that it meets two basic requirements:
1.There is no redundancy of data, all data is stored in only one place.
2.Data dependencies are logical, all related data items are stored together.
Normalization is important for many reasons, but chiefly because it allows databases to take up as little disk space as possible, resulting in increased performance.

1. Speak clearly and vary your tone to show you’re interested and enthusiastic.
2. Take time to think about each question before answering so you can give a good response.
3. Give examples from your experience that demonstrate your knowledge and skills.

General Tips : 
As the interviewer is looking to see how you think, rationalize and deal with complex problems, you should also explain your thought process so the interviewer can see the logic behind it.
As brainteaser questions are deliberately complex, it’s a good idea to practice them before the interview, to prepare you for the kind of questions you’re going to see.