Amazon Software Developer Interview Questions, Process, and Tips

2 Questions based on Data Structures

Q1. Median of 2 sorted arrays
Ans. 
Find the median of two sorted arrays
• Merge the two arrays into one sorted array and find the median

• Use binary search to find the median efficiently

• Handle edge cases like arrays of different lengths
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Q2. Minimum cost of ropes
Ans. 
The minimum cost of ropes can be calculated using a greedy algorithm approach.
• Calculate the cost of joining two smallest ropes at each step

• Add the cost to the total cost and update the list of ropes

• Repeat until only one rope is left
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Q1. LRU Cache implemetation
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Q2. Trapping rain water problem
Ans. 
Trapping rain water problem involves calculating the amount of water that can be trapped between buildings given their heights.
• Calculate the maximum height on the left and right of each building

• Subtract the building height from the minimum of the two maximum heights to get the water trapped at that building

• Sum up the water trapped at each building to get the total trapped water
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Round duration - 90 minutes
Round difficulty - Easy

90 minutes round Seven debugging questions, two coding questions, Behavioural questions

Q1. 
Maximum Path Sum Between Two Leaves
Given a non-empty binary tree where each node has a non-negative integer value, determine the maximum possible sum of the path between any two leaves of the given tree.
...read more
Ans. 
Find the maximum path sum between two leaf nodes in a binary tree.
• Traverse the tree to find the maximum path sum between two leaf nodes

• Consider both cases where the path passes through the root and where it doesn't

• Use recursion to calculate the sum of paths from each leaf node to the root
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Q2. 
Path In A Tree Problem Statement
Given a binary tree with 'N' nodes and a specific node 'X', your goal is to print the path from the root node to the specified node 'X'.
Explanation:
A binary tree is a ...read more
Ans. 
Given a binary tree and a target node, find the path from the root to the target node.
• Traverse the binary tree from the root to the target node using depth-first search (DFS).

• Store the path from the root to the target node while traversing the tree.

• Print the stored path as the output for each test case.

• Ensure uniqueness of node values and that the target node exists in the tree.
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Round duration - 60 minutes
Round difficulty - Medium

The interviewer directly stated with coding question. He asked me 2 coding questions and he was aspecting the optimal working code of both.

Q1. 
Boundary Traversal Problem Statement
Given a binary tree of integers, your task is to return the boundary nodes of this binary tree in an anti-clockwise direction starting from the root node.
Example:
I...read more
Ans. 
Return the boundary nodes of a binary tree in an anti-clockwise direction starting from the root node.
• Traverse the left boundary nodes in a top-down manner

• Traverse the leaf nodes from left to right

• Traverse the right boundary nodes in a bottom-up manner

• Avoid repeating nodes in the output

• Example: For input 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1, output should be 1 2 4 7 6 3
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Q2. 
Maximum Consecutive Ones Problem Statement
Given a binary array 'ARR' of size 'N', your task is to determine the maximum length of a sequence consisting solely of 1’s that can be obtained by converting at...read more
Ans. 
The task is to find the maximum length of a sequence of 1's by converting at most K zeroes into ones in a binary array.
• Iterate through the array and keep track of the current window of 1's and zeroes.

• Use a sliding window approach to find the maximum length of consecutive 1's by flipping at most K zeroes.

• Update the window based on the number of zeroes flipped and keep track of the maximum length found so far.

• Return the
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Round duration - 60 minutes
Round difficulty - Medium

The interviewer started with tell me about your self. Then he started asking about my previous intenship projects and some Common Hr questions like why you want to join amazon. This went for almost 30 minutes then he asked me to solve a coding question similar to Rotten Orange question.

Q1. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find the minimum time required to rot all fresh oranges in a grid.
• Use Breadth First Search (BFS) to simulate the rotting process.

• Track the time taken to rot all fresh oranges.

• Return -1 if not all fresh oranges can be rotten.

• Handle edge cases like empty grid or no fresh oranges.

• Example: For the given grid, it takes 4 seconds to rot all fresh oranges.
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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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2 hacker rank tests and one round of behavior

Q1. A basic tree question
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Q1. Design chess game
Ans. 
Design a chess game with all the necessary components and rules.
• Create a board with 64 squares (8x8 grid)

• Assign pieces to each player (16 pieces per player)

• Implement movement rules for each piece (e.g. pawn moves forward, bishop moves diagonally)

• Include special moves like castling and en passant

• Implement win conditions (checkmate, stalemate)

• Consider implementing features like undo move, AI opponent
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Q1. Graph and a greedy problem
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