Amazon Development Centre India Associate Software Engineer Interview Questions and Answers

Round duration - 60 Minutes
Round difficulty - Easy

4 Questions which were of Easy, Medium, and Hard level.

Q1. 
Lowest Common Ancestor of a Binary Tree III
The structure of a binary tree has been modified so that each node includes a reference to its parent node.
Problem Statement
You are provided with two nodes,...read more
Ans. 
This question is about finding the lowest common ancestor of two nodes in a binary tree with parent references.
• Traverse from the given nodes to their respective root nodes and store the paths in two separate lists.

• Compare the two lists and find the last common node.

• Return the last common node as the lowest common ancestor.
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Q2. 
Maximum Subarray Problem Statement
Ninja has been given an array, and he wants to find a subarray such that the sum of all elements in the subarray is maximum.
A subarray 'A' is considered greater than a...read more
Ans. 
The problem is to find a subarray with the maximum sum in a given array.
• Iterate through the array and keep track of the maximum sum and the current sum.

• If the current sum becomes negative, reset it to 0.

• Update the maximum sum if the current sum is greater.

• Also keep track of the start and end indices of the subarray with the maximum sum.

• Return the subarray using the start and end indices.
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Round duration - 50 Minutes
Round difficulty - Easy

Q1. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
The task is to find the next greater element for each element in an array.
• Iterate through the array from right to left.

• Use a stack to keep track of the elements that have a greater element to their right.

• For each element, pop elements from the stack until a greater element is found or the stack is empty.

• If a greater element is found, it is the next greater element for the current element.

• If the stack becomes empty, the...read more
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Q2. 
Trapping Rain Water Problem Statement
You are given a long type array/list ARR of size N, representing an elevation map. The value ARR[i] denotes the elevation of the ith bar. Your task is to determine th...read more
Ans. 
The question asks to find the total amount of rainwater that can be trapped in the given elevation map.
• Iterate through the array and find the maximum height on the left and right side of each bar.

• Calculate the amount of water that can be trapped at each bar by taking the minimum of the maximum heights on both sides and subtracting the height of the bar.

• Sum up the amount of water trapped at each bar to get the total amo...read more
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Round duration - 30 Minutes
Round difficulty - Easy

It is just a formality round, asked basic questions like relocation and joining date etc

Round duration - 60 Minutes
Round difficulty - Medium

This round was purely based on Data Structures and Algorithms . One has to be fairly comfortable in solving Algorithmic problems to pass this round . Both the questions asked were quite common and luckily I had already prepared them from CodeStudio and LeetCode.

Q1. 
Binary Tree Traversals Problem Statement
Given a Binary Tree with 'N' nodes, where each node holds an integer value, your task is to compute the In-Order, Pre-Order, and Post-Order traversals of the binar...read more
Ans. 
Compute the In-Order, Pre-Order, and Post-Order traversals of a Binary Tree given in level-order format.
• Implement functions to perform In-Order, Pre-Order, and Post-Order traversals of a Binary Tree.

• Use level-order input to construct the Binary Tree.

• Traverse the Binary Tree recursively to generate the required traversals.

• Ensure proper handling of null nodes represented by -1 in the input.

• Return the three traversals as ...read more
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Q2. 
Reverse Linked List Problem Statement
Given a Singly Linked List of integers, your task is to reverse the Linked List by altering the links between the nodes.
Input:
The first line of input is an intege...read more
Ans. 
Reverse a singly linked list by altering the links between nodes.
• Iterate through the linked list and reverse the links between nodes

• Use three pointers to keep track of the current, previous, and next nodes

• Update the links between nodes to reverse the list

• Return the head of the reversed linked list
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Round duration - 45 Minutes
Round difficulty - Medium

This round basically tested some concepts from Data Structures and File Manipulation .

Q1. 
Intersection of Two Arrays Problem Statement
Given two arrays A and B with sizes N and M respectively, both sorted in non-decreasing order, determine their intersection.
The intersection of two arrays in...read more
Ans. 
The problem involves finding the intersection of two sorted arrays efficiently.
• Use two pointers to iterate through both arrays simultaneously.

• Compare elements at the pointers and move the pointers accordingly.

• Handle cases where elements are equal and update the intersection array.

• Return the intersection array as the result.
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