SDE - 1

You have 'N' empty pens whose refills have been used up. You have 'R' rupees in your pocket. You have two choices of operations that you can perform each time.

1) Recycle 1 empty pen and get 'K' rupees as a reward.

2) Buy 1 refill for 'C' rupees and combine it with 1 empty pen to make one usable pen.

Your task is to find the maximum number of usable pens that you can get.

For example if you have 'N' = 5 , 'R' = 10 , 'K' = 2 , 'C' = 3. You can recycle one pen and get 2 rupees as a reward so you will have a total of 12 rupees. Now you can buy 4 refills and combine it with 4 pens to make it usable. So your answer is 4.

Why is the use of DBMS recommended? Explain by listing some of its major advantages.

You are given an array consisting of 'N' distinct positive integers and a number 'K'. Your task is to find the kth largest element in the array.

Example:

Consider the array {2,1,5,6,3,8} and 'K' = 3, the sorted array will be {8, 6, 5, 3, 2, 1}, and the 3rd largest element will be 5.

Note:

1) Kth largest element in an array is the kth element of the array when sorted in non-increasing order. 

2) All the elements of the array are pairwise distinct.

Explain the concepts of a Primary key and Foreign Key.

What are ACID properties? Explain them?

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

1. Push(num): Push the given number in the stack.
2. Pop: Remove and return the top element from the stack if present, else return -1.
3. Top: return the top element of the stack if present, else return -1.
4. getMin: Returns minimum element of the stack if present, else return -1.

For Example:

For the following input: 
1
5
1 1
1 2
4
2
3

For the first two operations, we will just insert 1 and then 2 into the stack which was empty earlier. So now the stack is => [2,1]
In the third operation, we need to return the minimum element of the stack, i.e., 1. So now the stack is => [2,1]
For the fourth operation, we need to pop the topmost element of the stack, i.e., 2. Now the stack is => [1]
In the fifth operation, we return the top element of the stack, i.e. 1 as it has one element. Now the stack is => [1]

So, the final output will be: 
1 2 1

Given a singly linked list of 'N' nodes. The objective is to determine the middle node of a singly linked list. However, if the list has an even number of nodes, we return the second middle node.

Note:

1. If the list is empty, the function immediately returns None because there is no middle node to find.
2. If the list has only one node, then the only node in the list is trivially the middle node, and the function returns that node.

You are given a string of lowercase characters. Your task is to rearrange (reorder) the string in such a way that no two adjacent characters are the same.

You have to return the rearranged string. If there exists more than one solution you can return any of them.If there is no such string you have to return “NO SOLUTION”. If your returned value is correct the program will print ‘CORRECT’ else ‘INCORRECT’.

For example :

If we are given a string "aabb", then the possible solutions are:

(i) abab
(ii) baba

We can see no two adjacent characters are the same in both strings.

So both (i) and (ii) are valid solutions.

You have been given a 9 X 9 2D matrix 'MATRIX' with some cells filled with digits(1 - 9), and some empty cells (denoted by 0).

You need to find whether there exists a way to fill all the empty cells with some digit(1 - 9) such that the final matrix is a valid Sudoku solution.

A Sudoku solution must satisfy all the following conditions-

1. Each of the digits 1 - 9 must occur exactly once in each row.
2. Each of the digits 1 - 9 must occur exactly once in each column.
3. Each of the digits 1 - 9 must occur exactly once in each of the 9, 3 x 3 sub-matrices of the matrix.

Note

1. There will always be a cell in the matrix which is empty.
2. The given initial matrix will always be consistent according to the rules mentioned in the problem statement.