Top 10 Must-Answer Coding Questions to Crack the Amazon Interview


by Sayantani Sanyal
March 22, 2022

It is crucial for any Amazon aspirant to prepare crucial coding questions beforehand

Coding and programming have become some of the most popular tech careers, making huge strides among tech aspirants. But to acquire positions in top companies like Amazon, Microsoft, IBM, Google, and others, these aspirants must be aware of essential algorithms, methods and should have a good hold over programming languages ​​such as Java, especially if they are applying for programming jobs. Companies like Amazon have quite a strict shortlisting and hiring process. Amazon is also considered one of the toughest tech giants to get through. It organizes online coding tests, and aspirants are required to thoroughly prepare these coding questions to get through the Amazon interview. These top coding questions differ in moderation according to the candidates’ previous working or educational experience and qualifications. In this article, we have listed the top coding questions and answers that Amazon interview candidates must answer and prepare for.

How can you find the first non-repeated character in a word?

A function needs to be written that accepts strings and returns the first non-repeated characters. In order to write a code that will return the first non-repeated letters, we can use the LinkedHashMap to store the character count. This HashMap follows the order of the insertion and characters are initialized in the same position as the in the string. The scammed string must be iterated using LinkedHashMap to choose the required entry with the value of 1.

Explain the meaning of a doubly linked list.

Doubly linked lists are categorized as a special type of linked list in which traversal across data elements can be done in both directions. This is made possible by the presence of two links in each node, one that links to the node next to it and another that connects to the before it.

What are dynamic data structures?

Dynamic data structures have the feature where they expand and contract as a program runs. It provides a very flexible method of data manipulation because it adjusts based on the size of the data that is to be manipulated.

How does variable declaration affect memory?

The amount of memory that is to be reserved or allocated depends on the type of data being stored in that variable. For instance, if a variable is declared to be ‘integer type’, 32 bits of memory storage will then be reserved for that particular variable.

How to remove a given character from String in Java?

One of the most simple solutions to this problem is to iterate over String by converting it into a character array and checking if the current character is the same as a given character to remove or not, or professionals can also add it to the StringBuilder. At the end of the iteration, they will have a StringBuilder with all characters, except the one which is asked to remove. One just needs to convert this StringBuilder into String, and they will have their solution ready.

Which sorting algorithm do you think is the best?

There are many sorting algorithms, that include bubble sort, quick sort, balloon sort, merge sort, radix sort, and others. But no algorithm can be considered as the best or the fastest because they have designed each for a specific type of data structure where it performs the best.

What is a Deque?

A deque is a double-ended queue. It is a structure in which the elements can be inserted or removed from either end.

What do you understand by a Recursion?

Recursion refers to a function calling itself based on a terminating condition. It uses LIFO and therefore makes use of the stack data structure.

How will you reverse the words in a target sentence without using library methods?

To effectively reverse a sentence, we must use regular expressions in Java to divide the given strings into spaces followed by applying the reverse () method from the Collections utility class. Once we have divided the strings using regex ‘\ s’, an array of words will be returned as a result. This also takes care of the words separated using multiple spaces. As soon as the array is returned, the coders can choose to create ArrayLists from these arrays followed by using the Collections. reverse () method. This reverses ArrayLists and every word will be reinitialized in the reverse order.

What is a Linked List?

Like an array, a linked list refers to a linear data structure in which the elements are not necessarily stored in a contiguous manner. It is basically a sequence of nodes, each node points towards the next node forming a chain-like structure.

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