JioStar Android Developer Interview Questions and Answers

Questions on data structure, algorithm, and Android development.

• To find maximum sum subarray, use Kadane's algorithm

• To separate zeroes and ones in array, use two pointers approach

• ViewModel is a class that stores and manages UI-related data

• RecyclerView is a flexible view for providing a limited window into a large data set

• To implement ViewModel, extend ViewModel class and override onCleared() method

Find the first missing positive number in an array of positive and negative integers.

• Sort the array in ascending order

• Iterate through the sorted array and find the first positive number that is missing

• If no positive number is missing, return the next positive number after the largest positive number in the array

The data structure to program a jigsaw puzzle program would be a graph.

• Use a graph data structure to represent the puzzle pieces and their connections.

• Each puzzle piece can be represented as a node in the graph.

• Edges between nodes represent the connections between puzzle pieces.

• To solve the puzzle, use graph traversal algorithms like depth-first search or breadth-first search.

• Apply puzzle-solving strategies like findin...read more

Times Internet Limited (TIL) is a digital products company that operates various online platforms and services.

• TIL is a subsidiary of Bennett Coleman & Co. Ltd (BCCL), which is India's largest media conglomerate.

• TIL operates popular websites and apps like Times of India, Economic Times, Gaana, MX Player, and Cricbuzz.

• TIL focuses on digital content, e-commerce, and technology solutions.

• TIL has a diverse portfolio of...read more

I transitioned to software development due to my passion for coding and problem-solving.

• I discovered my interest in coding during my civil engineering studies

• I took online courses and attended coding bootcamps to learn software development skills

• I completed projects and internships in software development to gain practical experience

• I enjoy the creativity and problem-solving aspects of software development

The average speed can be calculated by taking the harmonic mean of the two speeds.

• To calculate the harmonic mean, divide the sum of the speeds by the reciprocal of the sum of their reciprocals.

• In this case, the harmonic mean can be calculated as 2/(1/20 + 1/30) = 24 km/h.

The minimum number of steps to find the defective ball is 2.

• Divide the 8 balls into 3 groups of 3, 3, and 2 balls.

• Compare the weights of the two groups of 3 balls.

• If one group is heavier, divide it into 2 balls and compare their weights.

• If the two balls have different weights, the heavier ball is the defective one.

• If the two balls have the same weight, the remaining ball in the first group of 3 is the defective one.

Polymorphism is the ability of an object to take on many forms. It allows objects of different classes to be treated as the same type.

• Polymorphism is achieved through method overriding and method overloading.

• Method overriding allows a subclass to provide a specific implementation of a method that is already defined in its superclass.

• Method overloading allows multiple methods with the same name but different parameters ...read more

Operator overloading is the ability to redefine operators for custom classes.

• Allows operators to be used with custom classes

• Example: '+' operator can be used to concatenate strings

• Can improve readability and simplify code

Method overloading is having multiple methods with the same name but different parameters. Method overriding is having a method in a subclass with the same name, return type, and parameters as a method in its superclass.

• Method overloading is achieved within the same class.

• Method overriding occurs in a subclass that inherits from a superclass.

• Method overloading is determined at compile-time based on the number, type, an...read more

Design optimal data structures for LRU cache

• Use a doubly linked list to keep track of recently used items

• Use a hash table to store key-value pairs for quick access

• When an item is accessed, move it to the front of the linked list

• When the cache is full, remove the least recently used item from the back of the linked list and hash table

Convert a sorted array to balanced binary search tree

• Find the middle element of the array and make it the root of the tree

• Recursively construct the left subtree using the left half of the array

• Recursively construct the right subtree using the right half of the array

• Repeat until all elements are added to the tree

Reverse a singly linked list in groups of k in­place

• Divide the linked list into groups of k nodes

• Reverse each group of k nodes

• Connect the reversed groups to form the final linked list

A recursive routine to calculate a ^ n

• The base case is when n is 0, in which case the result is 1

• For any other value of n, the result is a multiplied by the result of a^(n-1)

• The recursive function should call itself with a^(n-1) as the new input

Design optimal data structure for never-ending stream of numbers for insertion, deletion, searching, kth largest and kth smallest.

• Use a balanced binary search tree like AVL or Red-Black tree for efficient insertion, deletion, and searching.

• Maintain two heaps, one for kth largest and one for kth smallest.

• For finding kth largest, use a min heap of size k and for kth smallest, use a max heap of size k.

• Alternatively, use a...read more

Search an element in sorted rotated array.

• Use binary search to find the pivot point where the array is rotated.

• Divide the array into two subarrays and perform binary search on the appropriate subarray.

• Handle the cases where the target element is at the pivot point or not present in the array.

Find the Kth largest element in an array.

• Sort the array in descending order and return the element at index K-1.

• Use a max heap to find the Kth largest element efficiently.

• Implement a quickselect algorithm to find the Kth largest element in linear time.

Reverse a linked list in groups of n elements.

• Divide the linked list into groups of n elements.

• Reverse each group individually.

• Connect the reversed groups to form the final linked list.

• Handle cases where the number of elements is not a multiple of n.

• Example: 1->2->3->4->5->6->7->8, n=3 -> 3->2->1->6->5->4->8->7

Find the median of two sorted arrays.

• Merge the two arrays into one sorted array and find the median.

• Use binary search to find the median in O(log(min(m, n))) time complexity.

• Handle edge cases like empty arrays or arrays of different lengths.

Count number of paths from (0, 0) to (m, n) in a matrix while crossing through some indexes were not allowed.

• Use dynamic programming to solve the problem

• Create a 2D array to store the number of paths

• Traverse the matrix and update the array based on the allowed paths

• Return the value at the last index of the array