Josh Technology Group Software Developer Intern Interview Questions, Process, and Tips

Round duration - 75 minutes
Round difficulty - Medium

It was a coding round.

Q1. 
Multiply Linked Lists Problem Statement
Your task is to multiply two numbers represented as linked lists and return the resultant multiplied linked list.
Explanation:
The multiplied list should be a lin...read more
Ans. 
Multiply two numbers represented as linked lists and return the resultant multiplied linked list.
• Create a function that takes two linked lists as input and returns the product as a linked list

• Traverse both linked lists to extract the numbers, multiply them, and create a new linked list for the product

• Handle carry over while multiplying digits and adding to the result linked list
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Q2. 
Binary Tree Diameter Problem Statement
Given a binary tree, determine the length of its diameter. The diameter is defined as the longest path between any two end nodes in the tree. The path's length is re...read more
Ans. 
The diameter of a binary tree is the longest path between any two end nodes in the tree.
• Traverse the tree to find the longest path between two leaf nodes.

• Use depth-first search (DFS) to calculate the height of each subtree.

• The diameter of the tree is the maximum of the sum of heights of left and right subtrees + 1.
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Round duration - 70 mintues
Round difficulty - Medium

It was an online coding round.

Q1. 
Add Two Numbers Represented by Linked Lists
Your task is to find the sum list of two numbers represented by linked lists and return the head of the sum list.
Explanation:
The sum list should be a linked...read more
Ans. 
Add two numbers represented by linked lists and return the head of the sum list.
• Traverse both linked lists simultaneously while keeping track of carry from previous sum

• Create a new linked list to store the sum of the two numbers

• Handle cases where one linked list is longer than the other by padding with zeros

• Update the sum and carry values accordingly while iterating through the linked lists
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Q2. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Ans. 
The task is to determine the maximum profit that can be achieved by performing up to two buy-and-sell transactions on a given set of stock prices.
• Iterate through the array of stock prices to find the maximum profit that can be achieved by buying and selling stocks.

• Keep track of the maximum profit after the first transaction and the maximum profit overall.

• Consider all possible combinations of buying and selling stocks t...read more
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Q3. 
Is Height Balanced Binary Tree Problem Statement
Determine if the given binary tree is height-balanced. A tree is considered height-balanced when:
1. The left subtree is balanced.
2. The right subtree is bala...read more
Ans. 
Check if a binary tree is height-balanced by ensuring left and right subtrees are balanced with a height difference of at most 1.
• Check if the left and right subtrees are balanced recursively.

• Calculate the height of each subtree and compare their heights.

• Return 'True' if the tree is height-balanced, 'False' otherwise.
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Round duration - 90 minutes
Round difficulty - Medium

In this round, three questions were asked and all of them were based on DSA.

Q1. 
Sum Root to Leaf Numbers
You are given an arbitrary binary tree consisting of N nodes, each associated with an integer value from 1 to 9. Each root-to-leaf path can be considered a number formed by concat...read more
Ans. 
Given a binary tree with node values, find the total sum of all root to leaf paths formed by concatenating node values.
• Traverse the tree in a depth-first manner, keeping track of the current path sum and updating it as you go along.

• When reaching a leaf node, add the current path sum to the total sum.

• Return the total sum modulo (10^9 + 7) as the final result.
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Q2. 
Maximum Non-Adjacent Subsequence Sum
Given an array of integers, determine the maximum sum of a subsequence without choosing adjacent elements in the original array.
Input:
The first line consists of an...read more
Ans. 
Find the maximum sum of a subsequence without choosing adjacent elements in an array.
• Use dynamic programming to keep track of the maximum sum at each index, considering whether to include the current element or not.

• At each index, the maximum sum can be either the sum of the current element and the element two positions back, or the sum at the previous index.

• Iterate through the array and update the maximum sum at each i...read more
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Q3. 
Rearrange Linked List Problem Statement
Given a singly linked list in the form 'L1' -> 'L2' -> 'L3' -> ... 'Ln', your task is to rearrange the nodes to the form 'L1' -> 'Ln' -> 'L2' -> '...read more
Ans. 
Rearrange the nodes of a singly linked list in a specific order without altering the data of the nodes.
• Use two pointers to split the linked list into two halves, reverse the second half, and then merge the two halves alternately.

• Ensure to handle cases where the number of nodes is odd or even separately.

• Keep track of the head and tail of each half to properly rearrange the nodes.

• Ensure to update the next pointers of the...read more
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Round duration - 120 minutes
Round difficulty - Medium

In this round, three questions were asked and all of them were based on DSA and a little bit about projects.

Q1. 
Minimum Jumps Problem Statement
Bob and his wife are in the famous 'Arcade' mall in the city of Berland. This mall has a unique way of moving between shops using trampolines. Each shop is laid out in a st...read more
Ans. 
Find the minimum number of trampoline jumps Bob needs to make to reach the final shop, or return -1 if impossible.
• Use BFS to traverse through the shops and keep track of the minimum jumps needed to reach each shop.

• If a shop has already been visited with fewer jumps, skip it.

• If a shop has Arr[i] = 0, it is impossible to reach the last shop.

• Return the minimum jumps to reach the last shop or -1 if impossible.
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Q2. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. 
Find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
• Use backtracking algorithm to explore all possible configurations

• Keep track of rows, columns, and diagonals to ensure queens do not threaten each other

• Recursively place queens on the board and backtrack when a conflict is found
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Q3. 
Flatten Binary Tree to Linked List
Transform a binary tree with integer values into a linked list by ensuring the linked list's nodes follow the pre-order traversal order of the binary tree.
Explanation:
...read more
Ans. 
Flatten a binary tree into a linked list following pre-order traversal order.
• Use the binary tree's right pointer as the linked list's 'next' pointer.

• Set each node's left pointer to NULL.

• Implement the solution without printing within the function.

• Follow pre-order traversal to flatten the binary tree into a linked list.
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Round duration - 20 mintues
Round difficulty - Easy

It was on the next day of the last technical round, I was on the same site as the technical interview round.

Round duration - 60 minutes
Round difficulty - Medium

Timing was late. Environment was good.

Q1. 
Dijkstra's Shortest Path Problem
Given an undirected graph with ‘V’ vertices (labeled 0, 1, ... , V-1) and ‘E’ edges, where each edge has a weight representing the distance between two connected nodes (X,...read more
Ans. 
Dijkstra's algorithm is used to find the shortest path from a source node to all other nodes in a graph with weighted edges.
• Implement Dijkstra's algorithm to find the shortest path distances from the source node to all other nodes.

• Use a priority queue to efficiently select the next node with the shortest distance.

• Initialize distances to all nodes as infinity except for the source node which is 0.

• Update distances to nei...read more
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Q2. 
Spiral Matrix Path Problem Statement
Given a N x M matrix of integers, print the spiral order of the matrix.
Input:
The input starts with an integer 'T' representing the number of test cases. Each test ...read more
Ans. 
The problem involves printing the spiral order of a given matrix of integers.
• Iterate through the matrix in a spiral order by keeping track of the boundaries.

• Print the elements in the order: top row, right column, bottom row, left column.

• Continue this process until all elements are printed in spiral order.
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Q3. 
0/1 Knapsack Problem Statement
A thief is planning to rob a store and can carry a maximum weight of 'W' in his knapsack. The store contains 'N' items where the ith item has a weight of 'wi' and a value of...read more
Ans. 
Yes, the 0/1 Knapsack problem can be solved using a space complexity of not more than O(W) using dynamic programming.
• Use a 2D array to store the maximum value that can be stolen for each weight capacity up to W and each item up to N.

• Iterate through each item and weight capacity, updating the maximum value that can be stolen based on whether the item is included or not.

• The final answer will be stored in the bottom-right...read more
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Round duration - 60 minutes
Round difficulty - Medium

Timing was late. Environment was good.

Q1. 
Dijkstra's Shortest Path Problem Statement
You are given an undirected graph with V vertices (numbered from 0 to V-1) and E edges. Each edge connects two nodes u and v and has an associated weight represe...read more
Ans. 
Dijkstra's algorithm is used to find the shortest path distance from a source node to all vertices in an undirected graph.
• Implement Dijkstra's algorithm to calculate shortest path distances

• Use a priority queue to efficiently select the next node to visit

• Initialize distances to all nodes as infinity, except for the source node as 0

• Update distances based on the weights of edges and choose the shortest path

• Handle disconne...read more
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Q2. 
Spiral Matrix Problem Statement
Given a two-dimensional matrix of integers, print the matrix in a spiral order.
Input:
The first line contains an integer 't' indicating the number of test cases. For eac...read more
Ans. 
Print a two-dimensional matrix in spiral order.
• Iterate through the matrix in a spiral order by keeping track of the boundaries.

• Print elements in the order: top row, right column, bottom row, left column.

• Repeat the process for inner submatrices until all elements are printed.
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Q3. 
0/1 Knapsack Problem Statement
A thief is planning to rob a store and can carry a maximum weight of 'W' in his knapsack. The store contains 'N' items where the ith item has a weight of 'wi' and a value of...read more
Ans. 
Yes, the 0/1 Knapsack problem can be solved using a space complexity of not more than O(W) using dynamic programming.
• Use a 1D array to store the maximum value that can be stolen for each weight from 0 to W.

• Iterate through the items and update the array based on the current item's weight and value.

• The final value in the array will be the maximum value that can be stolen within the weight capacity of the knapsack.
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Q1. 
Multiply Linked Lists Problem Statement
Your task is to multiply two numbers represented as linked lists and return the resultant multiplied linked list.
Explanation:
The multiplied list should be a lin...read more
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Q2. 
Longest Alternating Subsequence Problem
Given an array ARR of integers, determine the length of the longest alternating subsequence.
Input:
ARR = {Array elements}
Output:
Length of the longest alterna...read more
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Q3. 
Rotate Matrix K Times Problem Statement
Given a matrix, rotate its elements clockwise by 90 degrees, K times.
Each rotation by 90 degrees counts as one.
Input:
Line 1: Two integers M and N, denoting th...read more
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Q4. 
Add Two Numbers Represented by Linked Lists
Your task is to find the sum list of two numbers represented by linked lists and return the head of the sum list.
Explanation:
The sum list should be a linked...read more
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Q5. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Add your answer
Q6. 
Is Height Balanced Binary Tree Problem Statement
Determine if the given binary tree is height-balanced. A tree is considered height-balanced when:
1. The left subtree is balanced.
2. The right subtree is bala...read more
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Q7. 
Sum Root to Leaf Numbers
You are given an arbitrary binary tree consisting of N nodes, each associated with an integer value from 1 to 9. Each root-to-leaf path can be considered a number formed by concat...read more
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Q8. 
Remove BST Keys Outside Given Range
Given a Binary Search Tree (BST) and a specified range [min, max], your task is to remove all keys from the BST that fall outside this range. The BST should remain vali...read more
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Q9. 
Maximum Non-Adjacent Subsequence Sum
Given an array of integers, determine the maximum sum of a subsequence without choosing adjacent elements in the original array.
Input:
The first line consists of an...read more
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Q10. 
Minimum Jumps Problem Statement
Bob and his wife are in the famous 'Arcade' mall in the city of Berland. This mall has a unique way of moving between shops using trampolines. Each shop is laid out in a s...read more
Add your answer
Q11. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they a...read more
Add your answer
Q12. 
Closest Leaf in a Binary Tree
Ninja is stuck in a maze represented as a binary tree, and he is at a specific node ‘X’. Help Ninja find the shortest path to the nearest leaf node, which is considered an e...read more
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Round duration - 45 minutes
Round difficulty - Medium

Online coding round.
We could only write pseudo code and couldn't test against test cases.

Q1. 
Binary Tree Level Order Traversal
You are given a binary tree of integers. Your task is to return the level order traversal of the given tree.
Input:
The first line contains an integer 'T', representing...read more
Ans. 
Return the level order traversal of a binary tree given in level order.
• Use a queue to perform level order traversal of the binary tree

• Start by pushing the root node into the queue

• While the queue is not empty, dequeue a node, print its value, and enqueue its children
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Round duration - 50 minutes
Round difficulty - Easy

It was onsite face to face technical round where i was asked 2 coding questions.
It lasted for 40-50 minutes.

Q1. 
Kth Ancestor in a Binary Tree
You are given an arbitrary binary tree consisting of N nodes numbered from 1 to N, an integer K, and a node TARGET_NODE_VAL from the tree. Your task is to find the Kth ancest...read more
Ans. 
Find the Kth ancestor of a given node in a binary tree.
• Traverse the tree to find the path from the target node to the root node.

• Store the path in a list and return the Kth element from the end.

• Handle cases where the Kth ancestor does not exist by returning -1.
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Q2. 
Equilibrium Indices in a Sequence
You are given an array/list named 'SEQUENCE', which consists of 'N' integers. The task is to identify all equilibrium indices in this sequence.
Explanation:
An equilibr...read more
Ans. 
Identify equilibrium indices in a given sequence by finding positions where sum of elements before and after is equal.
• Iterate through the sequence and calculate prefix sum and suffix sum at each index

• Compare prefix sum and suffix sum to find equilibrium indices

• Handle edge cases where no equilibrium index exists

• Return the indices as a sequence of integers or an empty sequence
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Round duration - 50 minutes
Round difficulty - Medium

Only 7 students were shortlisted after the first face to face round out of 40 students.
The interviewer seemed cool and was trying to calm down me as i was getting nervous.
Again there were 2 coding questions.

Q1. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Reverse a singly linked list of integers and return the head of the reversed linked list.
• Iterate through the linked list and reverse the pointers to reverse the list

• Use three pointers to keep track of current, previous, and next nodes

• Update the head of the reversed linked list once the reversal is complete
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Round duration - 90 minutes
Round difficulty - Medium

This was the last technical round and there were only 5 students left at the end of day.
The interview started at around 6:30 in the evening.

Q1. 
Replace with Sum of Greater Nodes Problem Statement
Convert a given binary search tree (BST) with 'N' nodes into a Greater Tree. In the Greater Tree, each node's data should be updated to the sum of its o...read more
Ans. 
Convert a binary search tree into a Greater Tree by updating each node's data to the sum of its original data plus the data of all nodes with greater or equal values.
• Traverse the BST in reverse inorder (right, root, left) to update nodes with the sum of greater nodes.

• Keep track of the sum of greater nodes encountered so far while traversing.

• Update each node's data with the sum of greater nodes and continue traversal.
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Q2. 
Nuts and Bolts Problem
You are given a collection of 'N' nuts and 'N' bolts, each having unique sizes. Your objective is to match each nut with its corresponding bolt based on size, adhering to a one-to-o...read more
Ans. 
Matching nuts and bolts based on size in a one-to-one mapping strategy.
• Iterate through the nuts and bolts arrays to find matching pairs based on size.

• Use sorting algorithms like quicksort to efficiently match nuts and bolts.

• Ensure the implementation modifies the input arrays directly to reflect the proper matched order.
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