Google Software Developer Interview Questions, Process, and Tips

Q1. Few easy to moderate DSA questions
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How do project

Q1. Tell me about yourself
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Q2. What is your experience
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Q3. Elaborate your day to day job
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1-2 hrs of interview across data structure

Round duration - 75 minutes
Round difficulty - Medium

A 24 hour window was given to us and we can attempt the test anytime in between. It included 2 coding questions. One was easy-medium level and the other one was hard. Along with this 7 debugging MCQ's were given, however they were easy.

Q1. 
Minimum and Maximum Candy Cost Problem
Ram is in Ninjaland, visiting a unique candy store offering 'N' candies each with different costs. The store has a special offer: for every candy you purchase, you c...read more
Ans. 
Find minimum and maximum cost to purchase all candies with special offer of free candies.
• Iterate through the candy costs array and sort it in ascending order.

• For minimum cost, start from the lowest cost candy and take free candies until reaching the next higher cost candy.

• For maximum cost, start from the highest cost candy and take free candies until reaching the next lower cost candy.
Answered by AI
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Q2. 
Swap And Maximize Problem Statement
You are given a circular array consisting of N integers. Your task is to find the maximum sum of the absolute differences between adjacent elements by rearranging the a...read more
Ans. 
Find the maximum sum of absolute differences between adjacent elements in a circular array by rearranging the elements.
• Sort the array in non-decreasing order.

• Alternate between picking the smallest and largest elements to maximize the sum of absolute differences.

• Calculate the sum of absolute differences between adjacent elements in the rearranged array.
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Round duration - 75 minutes
Round difficulty - Hard

Q1. 
Connecting Ropes with Minimum Cost
You are given 'N' ropes, each of varying lengths. The task is to connect all ropes into one single rope. The cost of connecting two ropes is the sum of their lengths. Yo...read more
Ans. 
Connect ropes with minimum cost by merging two smallest ropes at a time.
• Sort the array of rope lengths in ascending order.

• Merge the two smallest ropes at a time and update the cost.

• Repeat until all ropes are merged into one.

• Return the total cost as the minimum cost to connect all ropes.
Answered by AI
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Round duration - 60 minutes
Round difficulty - Medium

This round was held on Hackerearth from 2:00 PM to 3:00 PM
This round had 2 questions of easy/medium difficulty. Both were based on concepts of DP.
The use of offline IDE was prohibited so we were supposed to code it on Hackerearth IDE itself.

Q1. 
Min Steps to One Using Dynamic Programming
Given a positive integer N, your task is to determine the minimum number of steps required to reduce N to 1.
Allowed Operations:
1) Subtract 1 from it: n = n -...read more
Ans. 
Find the minimum number of steps to reduce a positive integer to 1 using given operations.
• Use dynamic programming to store the minimum steps for each number from 1 to N.

• Iterate through each number from 1 to N and calculate the minimum steps based on the given operations.

• Consider the cases where you can either subtract 1, divide by 2, or divide by 3 to find the minimum steps.

• Return the minimum steps needed to reduce the
Answered by AI
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Q2. 
Longest Palindromic Substring Problem Statement
You are provided with a string STR of length N. The goal is to identify the longest palindromic substring within this string. In cases where multiple palind...read more
Ans. 
Identify the longest palindromic substring in a given string.
• Iterate through the string and expand around each character to find palindromes

• Keep track of the longest palindrome found

• Return the longest palindrome with the smallest start index
Answered by AI
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Round duration - 45 minutes
Round difficulty - Medium

The round was held on Google Meet and I was given 2 coding problems for which first I had to explain my approach and then I had to write code in Shared Google Docs and dry run on sample test cases and discuss Time and Space Complexity.
There were 2 interviewers and both were very friendly and helpful and tried to bring us to our comfort level first.

Q1. 
Boyer Moore Algorithm for Pattern Searching
You are given a string text and a string pattern. Your task is to find all occurrences of pattern in the string text and return an array of indexes of all those...read more
Ans. 
Implement Boyer Moore Algorithm to find all occurrences of a pattern in a text string.
• Implement Boyer Moore Algorithm for efficient pattern searching.

• Iterate through the text string and compare the pattern with each substring of the text.

• Return an array of indexes where the pattern is found in the text.

• If pattern not found, return an array containing -1.
Answered by AI
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Q2. 
Median in a Stream Problem Statement
Your task is to determine the median of integers as they are read from a data stream. The median is the middle value in the ordered list of numbers. If the list length...read more
Ans. 
Find median of integers in a data stream as they are read. Return medians after each new element.
• Use a min heap to store the larger half of the numbers and a max heap to store the smaller half.

• Keep the sizes of the two heaps balanced to efficiently find the median.

• If the total number of elements is odd, the median is the top element of the max heap.

• If the total number of elements is even, the median is the average of t
Answered by AI
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Round duration - 90 minutes
Round difficulty - Hard

This round was also virtual. It has some difficult questions when compared to the previous rounds.
This was also held on Google Meet with shared docs for writing code.
There were 2 interviewers and both were helpful.

Q1. 
Shortest Alternate Colored Path Problem
Given a directed graph consisting of 'N' nodes labeled from '0' to 'N-1'. Each edge in the graph is colored either 'red' or 'blue'. The graph may include self-edges...read more
Ans. 
The task is to compute the shortest path from node '0' to each node in a directed graph with alternating colored edges.
• Create a graph using the given red and blue edges.

• Use Breadth First Search (BFS) to find the shortest path from node '0' to each node with alternating colored edges.

• If no such path exists, set the answer to -1.

• Return the array of shortest path lengths for each node.
Answered by AI
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Q2. 
Spell Checker Problem Statement
You are provided with a list of strings, DICTIONARY[], representing the correct spellings of words, and a query string QUERY that may contain misspelled words. Your task is...read more
Ans. 
Implement a spell checker function that suggests correct spellings from a dictionary for a given query string.
• Iterate through the dictionary to check for matching prefixes with the query string.

• Return a list of suggestions if the query string is misspelled, otherwise return an empty list.

• Ensure all strings are in lowercase and within the specified constraints.

• Handle multiple test cases as per the input format.

• Example: ...read more
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Q3. 
The Skyline Problem
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette when viewed from a distance. Each building is ...read more
Ans. 
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette.
• Iterate through the buildings and create a list of critical points (x, y) where the height changes.

• Sort the critical points based on x-coordinate and process them to form the skyline.

• Merge consecutive horizontal segments of equal height into one to ensure no duplicates in the output.
Answered by AI
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Round duration - 60 minutes
Round difficulty - Medium

This round was held on Hackerearth from 2:00 PM to 3:00 PM
This round had 2 questions of easy/medium difficulty. Both were based on concepts of DP.
The use of offline IDE was prohibited so we were supposed to code it on Hackerearth IDE itself.

Q1. 
Min Steps to One Using Dynamic Programming
Given a positive integer N, your task is to determine the minimum number of steps required to reduce N to 1.
Allowed Operations:
1) Subtract 1 from it: n = n -...read more
Ans. 
Find the minimum number of steps to reduce a positive integer to 1 using dynamic programming.
• Use dynamic programming to keep track of the minimum steps for each number from 1 to N.

• Consider the three allowed operations and their impact on the number of steps.

• Start from N and work backwards to 1, updating the minimum steps for each number.

• Optimize the solution by storing the minimum steps for previously calculated number
Answered by AI
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Q2. 
Find the Longest Palindromic Substring
Given a string ‘S’ composed of lowercase English letters, your task is to identify the longest palindromic substring within ‘S’.
If there are multiple longest palin...read more
Ans. 
Find the longest palindromic substring in a given string, returning the rightmost one if multiple exist.
• Use dynamic programming to check for palindromes within the string.

• Keep track of the longest palindromic substring found so far.

• Return the rightmost longest palindromic substring if multiple exist.
Answered by AI
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Round duration - 45 minutes
Round difficulty - Medium

The round was held on Google Meet and I was given 2 coding problems for which first I had to explain my approach and then I had to write code in Shared Google Docs and dry run on sample test cases and discuss Time and Space Complexity.
There were 2 interviewers and both were very friendly and helpful and tried to bring us to our comfort level first.

Q1. 
Pattern Matching Problem Statement
Given a pattern as a string and a set of words, determine if the pattern and the words list align in the same sequence.
Input:
T (number of test cases)
For each test ca...read more
Ans. 
Given a pattern and a list of words, determine if the words align with the pattern.
• Create a mapping between characters in the pattern and words in the list.

• Check if the mapping preserves the order of characters in the pattern.

• Return 'True' if the sequence of words matches the order of characters in the pattern, otherwise return 'False'.
Answered by AI
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Q2. 
Running Median Problem
Given a stream of integers, calculate and print the median after each new integer is added to the stream.
Output only the integer part of the median.
Example:
Input:
N = 5  
Stre...read more
Ans. 
Calculate and print the median after each new integer is added to the stream.
• Use two heaps - a max heap to store the smaller half of the numbers and a min heap to store the larger half.

• Keep the sizes of the two heaps balanced or differ by at most 1 to get the median efficiently.

• When a new integer is added, compare it with the current median and insert it into the appropriate heap.

• If the sizes of the heaps differ by mor...read more
Answered by AI
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Round duration - 90 minutes
Round difficulty - Medium

This round was also virtual. It has some difficult questions when compared to the previous rounds.
This was also held on Google Meet with shared docs for writing code.
There were 2 interviewers and both were helpful.

Q1. 
Shortest Alternate Colored Path Problem
Given a directed graph consisting of 'N' nodes labeled from '0' to 'N-1'. Each edge in the graph is colored either 'red' or 'blue'. The graph may include self-edges...read more
Ans. 
The task is to compute the shortest path from node '0' to each node in a directed graph with alternating colored edges.
• Create a graph using the given red and blue edges.

• Use Breadth First Search (BFS) to find the shortest path from node '0' to each node.

• Alternate between red and blue edges while traversing the graph.

• If no path exists, set the answer to -1.

• Return the array of shortest path lengths for each node.
Answered by AI
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Q2. 
Spell Checker Problem Statement
You are provided with a list of strings, DICTIONARY[], representing the correct spellings of words, and a query string QUERY that may contain misspelled words. Your task is...read more
Ans. 
Given a list of correct spellings and a query string, return a list of suggestions if the query is misspelled.
• Iterate through the dictionary and check for matches with the query string using a prefix search algorithm.

• Return a list of suggestions if the query is misspelled, otherwise return an empty list.

• Handle multiple test cases by looping through each case and performing the spell check operation.
Answered by AI
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Q3. 
The Skyline Problem
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette when viewed from a distance. Each building is ...read more
Ans. 
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette.
• Iterate through the buildings and create a list of critical points (x, y) where the height changes.

• Sort the critical points based on x-coordinate and process them to form the skyline.

• Merge consecutive horizontal segments of equal height into one to ensure no duplicates in the output.
Answered by AI
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