Behtar Technology Private Limited Android Developer Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Medium

Online test which can be attempted anytime between 22 May 2020, 06:00 AM and 25 May 2020, 01:00 AM

Q1. 
Postfix Expression Evaluation Problem Statement
Given a postfix expression, your task is to evaluate the expression. The operator will appear in the expression after the operands. The output for each expr...read more
Ans. 
Evaluate postfix expressions by applying operators to operands in a given order.
• Iterate through the postfix expression and push operands onto a stack

• When an operator is encountered, pop the required number of operands from the stack, apply the operator, and push the result back onto the stack

• Continue until the entire expression is evaluated and the final result is left on the stack
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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 achieve each sum with different number of dice.

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

• Return the result modulo 10^9 + 7.

• Optimize the solution ...read more
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Round duration - 60 minutes
Round difficulty - Medium

June 25 2020
Timing: 12:00 pm to 1:00 pm
This round was completely devoted to coding. I was asked to introduce myself and then 2 coding questions were asked.

Q1. 
Find First and Last Positions of an Element in a Sorted Array
Given a sorted array ARR consisting of N integers and an integer X, find the first and last positions of occurrence of X in the array.
Note:
...read more
Ans. 
Find the first and last positions of an element in a sorted array efficiently.
• Use binary search to find the first occurrence of X in the array.

• Use binary search to find the last occurrence of X in the array.

• Handle cases where X is not present or present only once.

• Return the first and last positions as 0-based indices.
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Q2. 
Maze with N Doors and 1 Key Problem Statement
You are given an N x N maze where some cells have doors, and you have a key that can be used only once to open a door. Determine if there exists a path from t...read more
Ans. 
Determine if there exists a path from the top-left cell to the bottom-right cell of a maze with N doors and 1 key.
• Use depth-first search (DFS) or breadth-first search (BFS) to explore possible paths through the maze.

• Keep track of the cells visited and use the key only once to open doors.

• Check if the bottom-right cell is reachable after traversing the maze.

• Handle edge cases such as the top-left and bottom-right cells ha...read more
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Round duration - 60 minutes
Round difficulty - Medium

9th July 2020
6:30PM to 7:30PM

Round duration - 60 minutes
Round difficulty - Easy

23-July 2020
4:00 PM to 5:00 PM
Coding questions + Several questions on computer fundamentals and networking were asked in a rapid-fire manner.

Q1. 
Stock Trading Maximum Profit Problem
Given the stock prices for 'N' days, your goal is to determine the maximum profit that can be achieved. You can buy and sell the stocks any number of times but can onl...read more
Ans. 
The goal is to determine the maximum profit that can be achieved by buying and selling stocks on different days.
• Iterate through the stock prices and buy on the days when the price is lower than the next day's price, and sell on the days when the price is higher than the next day's price.

• Calculate the profit by summing up the differences between buying and selling prices.

• Repeat the process for each test case and output
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Round duration - 60 minutes
Round difficulty - Medium

6- Aug 2020
3:00 PM to 4:00 PM
Resceduled to: @5:30 PM
Projects, Fundamentals check, Behavioral, Coding

Q1. 
Path Counting in Directed Graph
Given a directed graph with a specified number of vertices V and edges E, your task is to calculate the total number of distinct paths from a given source node S to all ot...read more
Ans. 
Calculate total number of distinct paths from a given source node to all other nodes in a directed graph.
• Use dynamic programming to keep track of the number of paths from the source node to each node.

• Consider the modulo operation to handle large numbers efficiently.

• Start by initializing the number of paths from the source node to itself as 1.

• Iterate through all edges and update the number of paths for each destination ...read more
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