Trilogy Innovations Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Medium

It contains 20 MCQs, based on the output of the given code and next followed by 2 programming questions. To get qualified for the next round you need to solve the 2 programming questions completely. The next rounds will be interviews. They had given 3 days time to attempt the first round.

Q1. 
Maximum Path Sum in a Matrix
Given an N*M matrix filled with integer numbers, determine the maximum sum that can be obtained from a path starting from any cell in the first row to any cell in the last row...read more
Ans. 
Find the maximum sum path in a matrix from top row to bottom row by moving down or diagonally.
• Use dynamic programming to keep track of maximum sum at each cell.

• At each cell, the maximum sum is the current cell value plus the maximum of the three possible previous cells.

• Iterate through the matrix row by row and update the maximum sum at each cell.

• Return the maximum sum found in the last row as the result.
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Q2. 
Dice Throws Problem Statement
You are given D dice, each having F faces numbered from 1 to F. The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up num...read more
Ans. 
The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up numbers equals the given 'target' sum.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the number of ways to reach each sum with each dice.

• Iterate through the dice and sum values to fill up the array.

• Return the result modulo 10^9 + 7.

• Optimize the solution to use no more than O(S)
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Round duration - 50 minutes
Round difficulty - Hard

Q1. 
Palindrome Permutation - Problem Statement
Determine if a permutation of a given string S can form a palindrome.
Example:
Input:
string S = "aab"
Output:
"True"
Explanation:
The permutation "aba" o...read more
Ans. 
Check if a permutation of a string can form a palindrome.
• Create a frequency map of characters in the string.

• Count the number of characters with odd frequencies.

• If there is at most one character with an odd frequency, the string can form a palindrome.
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Q2. 
Longest Common Subsequence Problem Statement
Given two strings STR1 and STR2, determine the length of their longest common subsequence.
A subsequence is a sequence that can be derived from another sequen...read more
Ans. 
The problem involves finding the length of the longest common subsequence between two given strings.
• Implement a function to find the longest common subsequence length between two strings.

• Use dynamic programming to solve the problem efficiently.

• Iterate through the strings and build a matrix to store the lengths of common subsequences.

• Return the value in the bottom-right cell of the matrix as the result.
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Round duration - 90 minutes
Round difficulty - Easy

This was an online technical round on the mettl platform, the test window was open from 22 to 25 May 2020
The test had 28 mcqs and 2 coding questions.
The test was proctored. One needed to have webcam on.
A sample test link was provided before test to get familiar with the mettl platform.

Q1. 
Count Inversions Problem Statement
Given an integer array ARR of size N, your task is to find the total number of inversions that exist in the array.
An inversion is defined for a pair of integers in the...read more
Ans. 
Count the total number of inversions in an integer array.
• Iterate through the array and for each pair of elements, check if the conditions for inversion are met.

• Use a nested loop to compare each pair of elements efficiently.

• Keep a count of the inversions found and return the total count at the end.
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Q2. 
Find Pair with Maximum GCD in an Array
Given an array of positive integers, your task is to find the GCD (Greatest Common Divisor) of a pair of elements such that it is the maximum among all possible pair...read more
Ans. 
Find the pair with the maximum GCD in an array of positive integers.
• Iterate through all pairs of elements in the array.

• Calculate the GCD of each pair using Euclidean algorithm.

• Keep track of the maximum GCD found so far.

• Return the maximum GCD value.
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Round duration - 60 minutes
Round difficulty - Medium

Time : 12pm to 1pm
Mode of Interview : Amazon Chime Video
LiveCode : To write code, it was not a compiler
The interviewer was quite supportive.

Q1. 
Majority Element Problem Statement
Given an array/list 'ARR' consisting of 'N' integers, your task is to find the majority element in the array. If there is no majority element present, return -1.
Exampl...read more
Ans. 
Find the majority element in an array, return -1 if no majority element exists.
• Iterate through the array and keep track of the count of each element using a hashmap.

• Check if any element's count is greater than floor(N/2) to determine the majority element.

• Return the majority element or -1 if no majority element exists.
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Q2. 
Subarray with Equal Occurrences Problem Statement
You are provided with an array/list ARR of length N containing only 0s and 1s. Your goal is to determine the number of non-empty subarrays where the numbe...read more
Ans. 
Count the number of subarrays where the number of 0s is equal to the number of 1s in a given array of 0s and 1s.
• Iterate through the array and keep track of the count of 0s and 1s encountered so far.

• Use a hashmap to store the difference between the counts of 0s and 1s seen at each index.

• Increment the count of subarrays whenever the difference between the counts seen before matches the current difference.
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Round duration - 60 minutes
Round difficulty - Medium

Time : 11 am to 12am
Mode of Interview : Amazon Chime Video
LiveCode : To write code, it was not a compiler
The interviewer was quite supportive.

Q1. 
Sorted Linked List to Balanced BST Problem Statement
Given a singly linked list where nodes contain values in increasing order, your task is to convert it into a Balanced Binary Search Tree (BST) using th...read more
Ans. 
Convert a sorted linked list into a Balanced Binary Search Tree (BST) using the same data values.
• Create a function to convert the linked list to an array for easier manipulation.

• Implement a function to build a Balanced BST from the array recursively.

• Ensure the height difference of the subtrees is no more than 1 for each node.

• Use level order traversal to output the values of the BST nodes.

• Handle NULL nodes by representi
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Q2. 
Implement Stack with Linked List
Your task is to implement a Stack data structure using a Singly Linked List.
Explanation:
Create a class named Stack which supports the following operations, each in O(1...read more
Ans. 
Implement a Stack data structure using a Singly Linked List with operations in O(1) time.
• Create a class named Stack with getSize, isEmpty, push, pop, and getTop methods.

• Use a Singly Linked List to store the elements of the stack.

• Ensure each operation runs in O(1) time complexity.

• Handle edge cases like empty stack appropriately.

• Test the implementation with sample queries to verify correctness.
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