Amazon Transportation Services Software Developer Interview Questions and Answers

Round duration - 90 Minutes
Round difficulty - Medium

Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Validate Binary Search Tree Problem Statement
Your task is to determine if a given binary tree with 'N' nodes is a valid Binary Search Tree (BST). A BST is defined by the following properties:
• The lef...read more
Ans. 
Validate if a given binary tree is a valid Binary Search Tree (BST) based on its properties.
• Check if the left subtree of a node has only nodes with data less than the node's data.

• Verify if the right subtree of a node has only nodes with data greater than the node's data.

• Ensure that both the left and right subtrees are also binary search trees.

• Implement a validation function for a BST.

• Output 'true' if the binary tree is...read more
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Round duration - 60 Minutes
Round difficulty - Easy

Round duration - 87 minutes
Round difficulty - Medium

Timing : It was conducted in evening at 3 PM
The pacreception environment was very user friendly .
The platform was audio and video proctored.

Q1. 
Binary to Decimal Conversion
Convert a given binary number, represented as a string 'S' of size 'N', into its decimal equivalent integer and output it.
Input:
The first line contains an integer 'T', den...read more
Ans. 
Convert a binary string to its decimal equivalent integer.
• Iterate through the binary string from right to left, multiplying each digit by 2 raised to the power of its position.

• Add the results of the multiplication to get the decimal equivalent.

• Ensure the binary string consists only of '0' and '1' characters.

• Handle multiple test cases by repeating the conversion process for each case.
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Round duration - 80 minutes
Round difficulty - Medium

So This was a very interactive round . There were two interviewers , one male and one female . The male interviewer was quite experienced where as female interviewer was relatively new . The Interview started by a small introduction followed by some OOPS related questions where I was tested on how i perceive the concept of OOPS in real life . Then this conversation was followed by some core concepts of JAVA like abstract classes and interfaces . Then I was asked about my projects that i mentioned in my resume , then after some healthy discussion on those projects , the interviewer started to question about DBMS , I was asked some basic queries followed by some advanced queries and then followed by a discussion on SQL vs NoSQL . Then Interviewers asked me about my tech stack and the source of my technical knowledge. Then at last I was asked that why Blackrock and this concluded my Interview.

Q1. 
Ninja And The Triangle Problem Statement
Ninja is provided with 'N' stars and the task is to construct a triangle such that the 'i'th level of the triangle uses 'i' number of stars. The goal is to make th...read more
Ans. 
Given 'N' stars, construct a triangle with maximum height using 'i' stars in 'i'th level.
• Calculate the maximum height of the triangle using the formula: height = floor((-1 + sqrt(1 + 8 * N)) / 2)

• Iterate through each test case and calculate the maximum height for each 'N'.

• Output the maximum height for each test case.
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Round duration - 60 minutes
Round difficulty - Medium

test timing: 7-8 pm
2 programming questions
webcam proctored

Q1. 
Minimum Cost to Reach End Problem
You are provided with an array ARR of integers of size 'N' and an integer 'K'. The goal is to move from the starting index to the end of the array with the minimum possib...read more
Ans. 
Find minimum cost to reach end of array by jumping with constraints
• Use dynamic programming to keep track of minimum cost at each index

• Iterate through the array and update the minimum cost based on reachable indices within K steps

• Calculate cost to jump from current index to reachable indices and update minimum cost accordingly
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Round duration - 60 minutes
Round difficulty - Easy

The coding test was conducted on Hackerrank platform. The test was in the evening. There were two coding questions of easy difficulty. The test was proctored, our webcam was on but not the mic. Also we were not allowed to switch tabs.
About 360 students sat in this round out which 15 were shortlisted for the next interview round.

Q1. 
Maximum Equal Elements After K Operations
You are provided with an array/list of integers named 'ARR' of size 'N' and an integer 'K'. Your task is to determine the maximum number of elements that can be m...read more
Ans. 
Determine the maximum number of elements that can be made equal by performing at most K operations on an array of integers.
• Sort the array in non-decreasing order to easily identify the elements that need to be increased

• Calculate the difference between adjacent elements to determine the number of operations needed to make them equal

• Keep track of the total number of operations used and the maximum number of elements that...read more
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Q2. 
Count Pairs with Given Sum
Given an integer array/list arr and an integer 'Sum', determine the total number of unique pairs in the array whose elements sum up to the given 'Sum'.
Input:
The first line c...read more
Ans. 
Count the total number of unique pairs in an array whose elements sum up to a given value.
• Use a hashmap to store the frequency of each element in the array.

• Iterate through the array and for each element, check if (Sum - current element) exists in the hashmap.

• Increment the count of pairs if the complement exists in the hashmap.
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Frog jump dp problem

Q1. Microservices, Kubernetes
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Q2. Rbac and access control
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