Google Web Developer Interview Questions and Answers

Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Spiral Order Traversal of a Binary Tree Problem Statement
Given a binary tree with 'N' nodes, your task is to print the nodes in spiral order traversal.
Example:
Input:
The binary tree is represented i...read more
Ans. 
Print nodes of a binary tree in spiral order traversal.
• Use a queue to perform level order traversal of the binary tree.

• Alternate between printing nodes from left to right and right to left at each level.

• Handle null nodes represented by '-1' appropriately.

• Example: For input '1 2 3 -1 -1 4 5 -1 -1 -1 -1', the output should be '1 3 2 4 5'.
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Word Break Problem Statement
You are given a list of N strings called A. Your task is to determine whether you can form a given target string by combining one or more strings from A.
The strings from A c...read more
Ans. 
Given a list of strings, determine if a target string can be formed by combining one or more strings from the list.
• Iterate through all possible combinations of strings from the list to form the target string.

• Use recursion to try different combinations of strings.

• Check if the current combination forms the target string.

• Return true if a valid combination is found, otherwise return false.
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. Design an elevator system.
Ans. 
Design an elevator system for efficient vertical transportation.
• Divide building into zones to optimize elevator usage.

• Implement algorithms for efficient elevator scheduling.

• Include safety features like emergency stop buttons and overload sensors.

• Consider user interface for passengers to select floors and monitor elevator status.
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Round duration - 90 minutes
Round difficulty - Medium

The online coding round took place at 9:30 am in the morning. The platform was new so I got familiar with it in advance, a night before, to avoid any hassle during the test. There was camera proctoring and laptop screen sharing throughout the test. Multiple programming languages like Java, C, C++ and Python were allowed. There were 3 coding questions based on DSA. Questions were different for different candidates.

Q1. 
Distinct Strings With Odd and Even Swapping Allowed Problem Statement
You are provided with an array of strings, and your objective is to determine the number of unique strings within it.
A string is deeme...read more
Ans. 
Given an array of strings, determine the number of unique strings that cannot be transformed into another string by swapping characters at odd or even indices.
• Iterate through each string in the array and check if it can be transformed into another string by swapping characters at odd or even indices.

• Keep track of unique strings that cannot be transformed and return the count.

• Example: For array = ["abcd", "cbad", "bdac"...read more
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Q2. 
Rotational Equivalence of Strings Problem Statement
Given two strings 'P' and 'Q' of equal length, determine if string 'P' can be transformed into string 'Q' by cyclically rotating it to the right any num...read more
Ans. 
Check if one string can be transformed into another by cyclically rotating it to the right.
• Iterate through all possible rotations of string P and check if any of them match string Q.

• Use string concatenation to simulate cyclic rotations efficiently.

• Compare the rotated strings with string Q to determine if they are equivalent.
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Q3. 
Buses Origin Problem Statement
You have been provided with an array where each element specifies the number of buses that can be boarded at each respective bus stop. Buses will only stop at locations that...read more
Ans. 
Given an array representing number of buses at each bus stop, determine how many buses originate from each stop.
• Iterate through the array and for each element, increment the count of buses originating from the corresponding bus stop.

• Use an array to store the count of buses originating from each stop.

• Remember to consider the constraint of 1-based indexing for bus stops.
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Round duration - 45 Minutes
Round difficulty - Medium

The interview took place through Microsoft Teams at 2:00 pm. The platform was smooth and the interviewer was very friendly and told me that he isn't looking for bookish language answers but he only wants to check my understanding of CS subjects.

Q1. 
Longest Mountain Subarray Problem Statement
Given an array of integers representing the heights of mountains, determine the length of the longest subarray that forms a mountain shape.
A mountain subarray...read more
Ans. 
Find the length of the longest mountain subarray in an array of integers.
• Iterate through the array to find peaks.

• Expand from peaks to find ascending and descending slopes.

• Track the length of the mountain subarray and return the maximum length.
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Round duration - 55 Minutes
Round difficulty - Medium

The interview was conducted on Microsoft Teams and the interviewer was very friendly. He made sure I was comfortable and described his role at Microsoft.

Q1. 
Kth Largest Element Problem
Given an array containing N distinct positive integers and a number K, determine the Kth largest element in the array.
Example:
Input:
N = 6, K = 3, array = [2, 1, 5, 6, 3, ...read more
Ans. 
Find the Kth largest element in an array of distinct positive integers.
• Sort the array in non-increasing order and return the Kth element.

• Use a sorting algorithm like quicksort or heapsort for efficiency.

• Ensure the array contains distinct positive integers for accurate results.
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Q2. Can you describe the ACID properties in DBMS?
Ans. 
ACID properties in DBMS ensure data integrity and consistency.
• Atomicity: All transactions are either fully completed or fully aborted. For example, transferring money from one account to another should be completed in its entirety.

• Consistency: The database remains in a consistent state before and after the transaction. For example, if a constraint is violated during a transaction, the transaction will be rolled back.

• Is...read more
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Round duration - 60 Minutes
Round difficulty - Hard

The interview was conducted on Microsoft Teams and code was written on Notepad (screen shared). The interviewer was friendly and gave hints to reach the final solution.

Q1. 
Data Structure with Insert, Delete, and GetRandom Operations
Design a data structure that supports four operations: insert an element, remove an element, search for an element, and get a random element. E...read more
Ans. 
Design a data structure supporting insert, delete, search, and getRandom operations in constant time.
• Use a combination of hashmap and array to achieve O(1) time complexity for all operations.

• For insert operation, check if element exists in hashmap, if not add to array and hashmap.

• For remove operation, check if element exists in hashmap, if yes, remove from array and hashmap.

• For search operation, check if element exists...read more
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Q2. 
Convert BST to Sorted Doubly Linked List
You are given a Binary Search Tree (BST), and your task is to convert it into a sorted Doubly Linked List (DLL).
Example:
Consider the provided BST. The goal is ...read more
Ans. 
Convert a Binary Search Tree to a sorted Doubly Linked List efficiently.
• Implement a function to convert a BST to a sorted DLL.

• Use in-order traversal to efficiently convert the BST to DLL.

• Maintain pointers for the head and tail of the DLL.

• Ensure the left child of a node becomes the previous node and the right child becomes the next node in the DLL.
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Q3. What would your dream project be like?
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