K.R.Mangalam World School Interview Questions and Answers for Freshers

Round duration - 70 minutes
Round difficulty - Easy

Q1. Parth And His OCD
Parth is a nerd programmer. He has started learning array/list programming. Parth has received an array/list ‘ARR’ of ‘N’ positive integers as a gift. Parth’s OCD gets triggered every tim...read more
Ans. Brute Force
The basic idea of this approach is to iterate the whole ‘ARR’ from start and see if the element present at the current position satisfies the conditions or not. If the element at the current index is not as per requirement then we will find an element which can take that position from ‘ARR’ after that index and replace it with the current element. 
 
Here is the algorithm:
 
1. Run a loop for ‘i’ = 0...read more
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Q2. Find all occurrences
You are given a 'M' x 'N' matrix of characters, 'CHARACTER_MATRIX' and a string 'WORD'. Your task is to find and print all occurrences of the string in ...read more
Ans. DFS
We can use DFS to solve this problem. The idea is to start from each cell in the matrix and explore all eight paths possible and recursively check if they will lead to the solution or not. To make sure that the path is simple and doesn’t contain any cycles, we keep track of cells involved in the current path  and before exploring any cell, we ignore it if it is already covered in the current path.
 
We can f...read more
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Q3. Print Nodes at distance K from a given node
You are given an arbitrary binary tree, a node of the tree, and an integer 'K'. You need to find all such nodes which have a distance K from the given no...read more
Ans. DFS
• Create a map to store the parent of each node in the tree, Traverse the tree recursively (via depth-first search), at each step if the current node is not NULL. Store its parent in the map, then traverse the left and right subtree.
• Now assume that the given node is the root of the tree. In such a case, we can simply run a breadth-first search from the root, and track the current level of the tree. When the level = ‘K...read more
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Round duration - 50 minutes
Round difficulty - Easy

The nature of the interviewer was very kind. The test was proctored, our webcam and mic were on, and shared my screen.

Q1. Diagonal Traversal of a binary tree.
You have been given a binary tree of integers. You are supposed to find the diagonal traversal(refer to Example) of the given binary tree.
Example:
Consider lines at...read more
Ans. Map based approach
The idea is to use the Map to store all the nodes of a particular diagonal number. We will use preorder traversal to update the Map. The key of the Map will be the diagonal number and the value of the Map will be an array/list that will store all nodes belonging to that diagonal. 
 
The steps are as follows:
 
1. Assign the diagonal number of the root as 0.
2. Do a preorder traversal of the binary...read more
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Q2. Diameter of the binary tree.
You are given a Binary Tree. You are supposed to return the length of the diameter of the tree.
The diameter of a binary tree is the length of the longest path between any tw...read more
Ans. Recursion
The basic idea of this approach is to break the problem into subproblems. 
Now, there are three possible cases:
 
1. The diameter of the tree is present in the left subtree.
2. The diameter of the tree is present in the right subtree.
3. The diameter of the tree passes through the root node.
 
Let us define a recursive function, ‘getDiamter’, which takes the root of the binary tree as input parameter and return...read more
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Round duration - 50 minutes
Round difficulty - Medium

The nature of the interviewer was very kind, helped me when I stuck. The test was proctored, our webcam and mic were on, and shared my screen.

Q1. Next Greater Element
For a given array/list of integers of size N, print the Next Greater Element(NGE) for every element. The Next Greater Element for an element X is the first element on the right side of...read more
Ans. Brute Force
For every element in the array, we will run a loop on its right side. As soon as we find an element on its right side which is greater than it, we will break the loop, assign it as the NGE of this element, move forward, and do the same for the next element.
Space Complexity: O(1)Explanation:
O(1)
 
No extra space is used.
Time Complexity: O(n^2)Explanation:
O(N ^ 2),  Where N is the number of elements ...read more
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Q2. Subset Sum Equal To K
You are given an array/list ‘ARR’ of ‘N’ positive integers and an integer ‘K’. Your task is to check if there exists a subset in ‘ARR’ with a sum equal to ‘K’.
Note: Return true if ...read more
Ans. Recursion
The idea is to generate all possible subsets and check if any of them sums up to ‘K’. This can be done through recursion.
 
Here is the algorithm:
 
subsetSumToK(N , K , ARR):
1. Initialize integer variable ‘ANS’ = ‘helper(ARR, N, K)’. Here ‘helper’ is the recursive function that returns true/false.
2. If ‘ANS’ is equal to 1 then:
   • Return true.
3. Else:
   • Return false.
 
helper(ARR, N, K):
1. Base case: If ‘N’ is less tha...read more
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Round duration - 50 minutes
Round difficulty - Easy

The nature of the interviewer was very kind, helped me when I stuck. The test was proctored, our webcam and mic were on, and shared my screen.

Q1. Buy and Sell Stock
You are Harshad Mehta’s friend. He told you the price of a particular stock for the next ‘N’ days. You can either buy or sell a stock. Also, you can only complete at most 2-transactions....read more
Ans. Recursion
This problem can be solved by solving its subproblems and then combining the solutions of the solved subproblems to solve the original problem. We will do this using recursion.
Basically, we have to buy the stock at the minimum possible price and sell at the maximum possible price, keeping in mind that we have to sell the stock before buying it again.
 
 
Below is the detailed algorithm: 
 
1. Call ...read more
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Q2. DBMS Questions
SQL command
ACID properties
Difference between unique primary and foreign key.
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Q3. OS Questions
What is segementation.
Difference between internal and external fragmentation.
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