42Gears Mobility Systems Interview Questions, Process, and Tips for Freshers

Aptitude Had around 50 Questions which cover Logical,Quantitative, Code snippets

Q1. Two Sum in Coding
Ans. 
Find two numbers in an array that add up to a specific target value.
• Use a hashmap to store the difference between the target value and each element in the array.

• Iterate through the array and check if the current element's complement exists in the hashmap.

• Return the indices of the two numbers that add up to the target value.
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Q2. Differences in final,Finally,Finalize
Ans. 
final, finally, and finalize are related terms in programming but have different meanings and usage
• final is a keyword in Java used to restrict inheritance, method overriding, and variable reassignment

• finally is a block of code in exception handling that always executes, regardless of whether an exception is thrown

• finalize is a method in Java used for cleanup operations before an object is garbage collected
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Q3. Basic Sql operations
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Q1. Array List Implementation in Stack for Push and pop
Ans. 
Array List can be implemented in a stack by using an array and keeping track of the top element.
• Create an array to store the elements of the stack.

• Keep track of the top element using a variable.

• For push operation, add the element to the top of the stack and increment the top index.

• For pop operation, remove the top element and decrement the top index.
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Q2. Finding 3rd Largest Number in an Array without using Sort
Ans. 
Find 3rd largest number in array without sorting
• Iterate through array to find largest, 2nd largest, and 3rd largest numbers

• Keep track of these numbers as you iterate

• Return the 3rd largest number found
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Q3. Finding the min number of Swap in Sorting of Array
Ans. 
To find the minimum number of swaps needed to sort an array
• Use graph theory to find cycles in the array

• Count the number of swaps needed to fix each cycle

• Add up the swaps needed for all cycles to get the total minimum swaps
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Round duration - 180 Minutes
Round difficulty - Easy

It was from 8 to 11 in the morning. Basic aptitude MCQs were there and 2 coding questions were there.

Q1. 
Expression Equality Checker
Given two strings representing expressions in variables, determine if they are equivalent. Return 'YES' if the expressions are identical and 'NO' if they are different. Each ex...read more
Ans. 
Check if two expressions are equivalent by evaluating them with different variable assignments.
• Parse the expressions to evaluate them with different variable assignments.

• Use a stack to keep track of operands and operators while evaluating the expressions.

• Compare the results of both expressions to determine if they are equivalent.
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Q2. 
Longest Increasing Subsequence Problem Statement
Given an array of integers with 'N' elements, determine the length of the longest subsequence where each element is greater than the previous element. This...read more
Ans. 
Find the length of the longest strictly increasing subsequence in an array of integers.
• Use dynamic programming to solve this problem efficiently.

• Initialize an array to store the length of the longest increasing subsequence ending at each index.

• Iterate through the array and update the length of the longest increasing subsequence for each element.

• Return the maximum value in the array as the result.
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Round duration - 32 Minutes
Round difficulty - Easy

It was my first face to face technical round. DSA questions of easy-medium type were asked. And some discussion on the project was there.

Q1. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, it indicates the presence of a cycle in the linked list.

• To optimize, use Floyd's cycle detection algorithm for O(N) time complexity and O(1) space complexity.
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Q2. 
Convert Binary Tree to Mirror Tree
Convert a given binary tree into its mirror tree, where the left and right children of all non-leaf nodes are interchanged.
Input:
An integer ‘T’ denoting the number o...read more
Ans. 
Convert a binary tree into its mirror tree by interchanging left and right children of non-leaf nodes.
• Traverse the tree in a recursive manner and swap the left and right children of each node.

• Modify the binary tree in place to get the mirror, without creating a new tree.

• Use a temporary variable to swap the left and right children of each node.
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Round duration - 45 Minutes
Round difficulty - Medium

It was technical plus HR round

Q1. 
Matrix Element Cube Sum Problem
For a given M x N sized 2D array 'MATRIX', find and return the value of (i * i + j * j) for elements where the sum of the cubes of its digits equals the element itself. Her...read more
Ans. 
Find and return the value of (i * i + j * j) for elements in a 2D array where the sum of the cubes of its digits equals the element itself.
• Iterate through the 2D array and check if the sum of the cubes of the digits equals the element itself.

• Calculate (i * i + j * j) for elements that satisfy the condition.

• Return the calculated values as output.

• If no element satisfies the condition, return -1.
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