Amazon Software Developer Interview Questions and Answers for Freshers

Q1. What is bfs and dfs ?
Ans. 
BFS (Breadth First Search) and DFS (Depth First Search) are algorithms used for traversing or searching tree or graph data structures.
• BFS explores all the neighbor nodes at the present depth prior to moving on to the nodes at the next depth level.

• DFS explores as far as possible along each branch before backtracking.

• BFS uses a queue data structure while DFS uses a stack or recursion.

• Example: BFS can be used to find the ...read more
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Q2. What type of problem needs dp to solve ?
Ans. 
Dynamic programming is used to solve problems that can be broken down into overlapping subproblems and have optimal substructure.
• DP is used for problems with optimal substructure, where the solution can be constructed from optimal solutions of its subproblems.

• DP is used for problems with overlapping subproblems, where the same subproblems are solved multiple times.

• Examples include Fibonacci sequence, shortest path prob...read more
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Q1. Why you join this company
Ans. I don't have personal experiences, feelings, or the ability to make decisions, so I haven't joined any company, including Amazon.
Answered by Abhijeet Shukla
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Q2. I am join this company because this is my dream company
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Q1. Depth of binary tree?
Ans. 
The depth of a binary tree is the number of edges on the longest path from the root node to a leaf node.
• Depth of a binary tree can be calculated recursively by finding the maximum depth of its left and right subtrees and adding 1.

• For example, a binary tree with only a root node has a depth of 0, while a binary tree with one root node and two leaf nodes has a depth of 1.

• The depth of a binary tree can also be visualized ...read more
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Q2. Reverse linked list
Ans. 
Reversing a linked list involves changing the direction of its nodes to point to the previous node instead of the next.
• Iterative approach: Use three pointers (prev, current, next) to reverse the links.

• Example: For list 1 -> 2 -> 3, after reversal it becomes 3 -> 2 -> 1.

• Recursive approach: Reverse the rest of the list and adjust the pointers accordingly.

• Example: In a recursive call, reverse 2 -> 3 first, ...read more
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Round duration - 90 Minutes
Round difficulty - Medium

Timing-90 Duration Of Assessment 
you need to give the test within 5 days of getting the test mail.

Test is conducted virtually through Hackerrank platform and after that it redirects to Amazon page where we need to answer questions related to Amazon’s Leadership Principles and workstyles.

Q1. 
Unique Paths Problem Statement
Given the dimensions of an M x N matrix, determine the total number of unique paths from the top-left corner to the bottom-right corner of the matrix.
Allowed moves are onl...read more
Ans. 
The problem involves finding the total number of unique paths from the top-left corner to the bottom-right corner of an M x N matrix by moving only right or down.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the number of unique paths for each cell in the matrix.

• Initialize the first row and first column with 1 as there is only one way to reach each cell in those rows and columns.

• F...read more
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Q2. 
Left View of a Binary Tree
Given a binary tree, your task is to print the left view of the tree. The left view of a binary tree contains the nodes visible when the tree is viewed from the left side.
Inpu...read more
Ans. 
Print the left view of a binary tree, containing nodes visible from the left side.
• Traverse the tree level by level and print the first node of each level.

• Use a queue to keep track of nodes at each level.

• Handle null nodes represented by -1 in the input.
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Round duration - 60 Minutes
Round difficulty - Hard

We need to solve 1 or 2(based on interviewer) coding question within 1 hour in which we need to explain our approach before writing the code and we need to give optimal solution of the approach.

Q1. 
Minimum Jumps Problem Statement
Bob and his wife are in the famous 'Arcade' mall in the city of Berland. This mall has a unique way of moving between shops using trampolines. Each shop is laid out in a st...read more
Ans. 
Find the minimum number of jumps Bob needs to make from shop 0 to reach the final shop, or return -1 if impossible.
• Use Breadth First Search (BFS) to find the minimum number of jumps needed.

• Keep track of the maximum reachable index at each step.

• If the maximum reachable index is less than the current index, return -1 as it's impossible to reach the last shop.
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Questions like leetcode, a lot of double linked lists

Q1. The last time i was failed
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Q2. How i deal with failure
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Round duration - 60 minutes
Round difficulty - Easy

There was 2 coding questions
Based on ds and algorithms

Q1. 
Count Inversions Problem Statement
Given an integer array ARR of size N, your task is to find the total number of inversions that exist in the array.
An inversion is defined for a pair of integers in the...read more
Ans. 
Count the total number of inversions in an integer array.
• Iterate through the array and for each pair of elements, check if the conditions for inversion are met.

• Use a nested loop to compare each element with all elements to its right.

• Keep a count of the inversions found and return the total count at the end.
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Q2. 
Kth Smallest Element in an Unsorted Array
Given an unsorted array arr of distinct integers and an integer k, your task is to find the k-th smallest element in the array.
Input:
The first line of input c...read more
Ans. 
Find the k-th smallest element in an unsorted array of distinct integers.
• Sort the array and return the k-th element.

• Use a min-heap to find the k-th smallest element efficiently.

• Implement quickselect algorithm to find the k-th smallest element in linear time.
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Round duration - 45 minutes
Round difficulty - Easy

It was easy and the interviewer is very friendly

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing their sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with the comparison.
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Q2. 
Longest Increasing Subsequence Problem Statement
Given 'N' students standing in a row with specific heights, your task is to find the length of the longest strictly increasing subsequence of their heights...read more
Ans. 
Find the length of the longest strictly increasing subsequence of heights of students in a row.
• Iterate through the heights array and for each element, find the length of the longest increasing subsequence ending at that element.

• Use dynamic programming to keep track of the longest increasing subsequence length for each element.

• Return the maximum length found in the dynamic programming array as the result.
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Q3. 
Find Missing Number In String Problem Statement
You have a sequence of consecutive nonnegative integers. By appending all integers end-to-end, you formed a string S without any separators. During this pro...read more
Ans. 
Given a string of consecutive nonnegative integers with one missing number, find the missing integer.
• Iterate through the string and check for missing numbers by comparing adjacent integers

• Calculate the sum of the original sequence and the sum of the integers in the string to find the missing number

• Handle cases where there are multiple missing numbers or the string is invalid
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Round duration - 20 minutes
Round difficulty - Medium

Asked general questions based on family
Spoke about ctc and relocation