15 Most-Asked Amazon Interview Questions With Answers
Amazon is a technology-driven company that relies on its software infrastructure. The giant e-commerce platform needs experts who can optimize its ecosystem. To land your dream job, you must prove your coding skills during the Amazon interview process. If you need help figuring out where to start the preparation, this guide is the perfect place.
To help you, we have compiled a list of the top 15 coding questions asked during Amazon interviews. The answers will teach you the fundamental concepts required to navigate difficult problem-solving questions. They will also help you sharpen your coding abilities so that you can learn to code with confidence during the interview.
Arrays
Amazon coding interviews focus on arrays as they store and manipulate collections of elements. They allow for fast access, insertion, deletion, and searching. Expertise in arrays demonstrates your understanding of data structures and algorithms. Amazon seeks candidates who can handle large datasets and build scalable systems, because these tasks showcase your critical thinking skills and ability to process data efficiently. In a nutshell, you need to show your problem-solving skills through the efficient use of arrays.
The best way to prepare is to practice. Brush up your concepts of arrays by solving the following problems:
Find the missing number in the array
Problem Statement
You are given an array containing 'n' distinct numbers taken from the range 0 to 'n'n. Since the array has only 'n' numbers out of the total 'n+1' numbers, find the missing number.
Determine if the sum of two integers is equal to the given value
Problem Statement
Given an array of integers and a value, determine if there are any two integers in the array whose sum is equal to the given value.
Linked Lists
Linked lists are another important data structure required for Amazon coding interviews. They provide a more cost-effective way of inserting and deleting data elements. With a strong foundation in using linked lists, you can traverse, change, and manipulate data. Moreover, using linked lists in algorithms improves the solution's scalability.
See if you can solve these problems:
Merge two sorted linked lists
Problem Statement
Given two sorted linked lists, merge them so that the resulting linked list is also sorted.
Copy linked list with arbitrary pointer
Problem Statement
You are given a linked list where the node has two pointers. The first is the regular ‘next’ pointer. The second pointer is called ‘arbitrary_pointer’ and it can point to any node in the linked list.
Your job is to write code to make a deep copy of the given linked list. Here, deep copy means that any operations on the original list (inserting, modifying and removing) should not affect the copied list.
Trees
You must know all the essential data structures to write the fastest algorithm. A key part of your interview preparation is developing a solid understanding of the application of tree data structure. In the context of Amazon, you can use trees for the following functions:
- Storing and retrieving hierarchical data
- Building decision trees for machine learning applications
- Constructing data structures for natural language processing
Level order traversal of a binary tree
Problem Statement
Given the root of a binary tree, display the node values at each level. Node values for all levels should be displayed on separate lines.
Determine if a binary tree is a binary search tree
Problem Statement
Given a Binary Tree, figure out whether it’s a Binary Search Tree. In a binary search tree, each node’s key value is smaller than the key value of all nodes in the right subtree, and are greater than the key values of all nodes in the left subtree i.e. L < N < R..
Strings
You can extract, transform, and analyze textual data if you are good at string manipulation. Text data plays a crucial role in Amazon due to the website’s use of search queries, product descriptions, and more.
You can try solving these problems to see if you're ready for this topic:
String segmentation
Problem Statement
Given a dictionary of words and an input string tell whether the input string can be completely segmented into dictionary words.
Reverse words in a sentence
Problem Statement
Given a string, find the length of the longest substring which has no repeating characters.
Dynamic Programming
Dynamic programming is a systematic way to solve complex problems by breaking them down into overlapping subproblems and then solving them. This reduces the computation cost. It is a helpful tool for Amazon because they need it to optimize their system in various ways. This includes the optimization of inventory management, supply chains, route planning, and pricing strategies.
Test yourself with this coding problem:
How many ways can you make change with coins and a total amount
Problem Statement
Given a dictionary of words and an input string tell whether the input string can be completely segmented into dictionary words.
Math and Stats
Mathematics and statistics play a significant role in Amazon's business. You can use math and stats to identify patterns and relationships in the vast amount of available data. Having a solid foundation in math and stats will help you with the following tasks:
- Designing efficient Algorithms
- Working with machine learning models
- Quantitative analysis
- Making data-driven decisions
Find Kth permutation
Problem Statement
Given a set of ‘N’ elements, find the Kth permutation.
Find all subsets of a given set of integers
Problem Statement
You are given a set of integers and you have to find all the possible subsets of this set of integers.
Backtracking
Backtracking means exploring the problem space to find the best solution. You can apply this technique through a trial-and-error approach to the choices.
Amazon faces many constraint-based problems, like scheduling, resource allocation, and logistics. You can solve these challenges by iterating combinations. Then, you can choose the most workable one.
Solve this question now to test yourself:
Print balanced brace combinations
Problem Statement
Print all braces combinations for a given value 'N' so that they are balanced.
Graphs
A graph is a tool used to depict a group of connected elements. You can use them to simulate real-world scenarios by applying graph algorithms.
Amazon uses graphs to analyze customer behavior and market trends, among other things. The personalized recommendations feature for customers also uses graphs. Amazon Web Services (AWS) also uses graph-based systems for distributed computing. Graphs can help with the following:
Efficient routing Optimization Resource allocation If you want to test your understanding of graphs, try solving this problem:
Clone a directed graph
Problem Statement
Given the root node of a directed graph, clone this graph by creating its deep copy so that the cloned graph has the same vertices and edges as the original graph.
Sorting and Searching
Amazon deals with large amounts of data. This is why you need to have a strong understanding of searching algorithms in order to create efficient search functionalities. Sorting algorithms are also valuable in identifying patterns in large data sets.
Do you know which search or sort algorithm to choose? The time and space complexity of the algorithm will help you decide. This, in turn, optimizes the system's performance.
To assess your skills in sorting and searching, try out these challenges:
Find the High/Low index
Problem Statement
Given an array of points in the a 2D plane, find ‘K’ closest points to the origin.
Search rotated array
Problem Statement
Given an unsorted array of numbers, find the top ‘K’ frequently occurring numbers in it.
