Google Interview Questions and Guide

Algorithmic depth and clean, well-tested code. Expect follow-ups that change constraints mid-problem. System design emphasizes scale and trade-offs.

The Google interview loop

1. Recruiter screen
2. 1–2 technical phone screens (coding)
3. Onsite: 3–4 coding, 1 system design (L5+), 1 Googleyness & leadership
4. Hiring committee + team match

Google interview questions

• Design a URL Shortener
• Design a Distributed Rate Limiter
• Design Uber
• Design a Web Crawler
• Design Top-K Trending Videos
• Design Dropbox
• Design YouTube
• Design Google Docs
• Design Search Autocomplete
• Design an Ad Click Aggregator
• Design Yelp (Proximity Search)
• Design Google Calendar
• Design Google Maps
• Design Online Chess
• Design LeetCode
• Design Airbnb
• Design Spotify
• Design Zoom (Video Conferencing)
• Design Instagram
• Design Gmail
• Design Facebook Live Comments
• Design Strava
• Design a Price Tracker
• Design Google News
• Design a Distributed File System
• Design a Real-Time Leaderboard
• Design a Remote Devbox
• Design a Crossword Puzzle Solver
• Design Smart Grid Device Control
• Design a Content Delivery Network (CDN)
• Design a Metrics Monitoring & Alerting System
• Design a Distributed Lock Service
• Design Sora (Text-to-Video)
• Trapping Rain Water
• Container With Most Water
• Majority Element (Boyer–Moore Vote)
• Find the Duplicate Number
• Find the First Occurrence (KMP)
• Best Time to Buy and Sell Stock
• Valid Palindrome
• Valid Palindrome II
• Valid Word Abbreviation
• Merge Sorted Array
• Move Zeroes
• Longest Common Prefix
• Rotate Image
• Spiral Matrix
• Next Permutation
• Set Matrix Zeroes
• Longest Repeating Character Replacement
• Max Consecutive Ones III
• Minimum Size Subarray Sum
• First Missing Positive
• Text Justification
• Remove Duplicates from Sorted Array
• Rotate Array
• Squares of a Sorted Array
• Two Sum II - Input Array Is Sorted
• Zigzag Conversion
• 4Sum
• 3Sum Closest
• Fruit Into Baskets
• Permutation in String
• String Compression
• Reverse Words in a String
• Subarray Product Less Than K
• Game of Life
• Majority Element II
• Remove Element
• Merge Strings Alternately
• Maximum Average Subarray I
• Is Subsequence
• Reverse Vowels of a String
• Maximum Product of Three Numbers
• Remove Duplicates from Sorted Array II
• Increasing Triplet Subsequence
• Frequency of the Most Frequent Element
• Maximum Points You Can Obtain from Cards
• Number of Substrings Containing All Three Characters
• Substring with Concatenation of All Words
• Rotate String
• Longest Substring with At Least K Repeating Characters
• Reverse Pairs
• Find Pivot Index
• Rearrange Array Elements by Sign
• Count Binary Substrings
• Can Make Arithmetic Progression From Sequence
• Find Missing and Repeated Values
• Find All Numbers Disappeared in an Array
• Valid Triangle Number
• Third Maximum Number
• Maximum Sum of Distinct Subarrays With Length K
• Maximum Number of Vowels in a Substring of Given Length
• Shortest Unsorted Continuous Subarray
• Longest Substring with At Most K Distinct Characters
• Longest Mountain in Array
• Sort an Array
• Toeplitz Matrix
• Range Sum Query - Immutable
• Range Sum Query 2D - Immutable
• Product of the Last K Numbers
• Subarray Sum Equals K
• Two Sum
• Longest Consecutive Sequence
• Contiguous Array (Equal 0s and 1s)
• Valid Anagram
• Isomorphic Strings
• Valid Sudoku
• Continuous Subarray Sum
• Subarray Sums Divisible by K
• Happy Number
• Logger Rate Limiter
• Contains Duplicate
• Ransom Note
• Word Pattern
• Design HashMap
• Count Number of Nice Subarrays
• Binary Subarrays With Sum
• LFU Cache
• Intersection of Two Arrays
• Repeated DNA Sequences
• Group Shifted Strings
• Design Underground System
• Find All Duplicates in an Array
• Longest Palindrome
• Analyze User Website Visit Pattern
• Unique Number of Occurrences
• Subarrays with K Different Integers
• Brick Wall
• K-diff Pairs in an Array
• Max Number of K-Sum Pairs
• Jewels and Stones
• Find Common Characters
• Shortest Word Distance
• Shortest Word Distance II
• Sort Array by Increasing Frequency
• Find the Cycle Entry
• Merge K Sorted Lists
• Add Two Numbers
• Swap Nodes in Pairs
• Rotate List
• Odd Even Linked List
• Remove Duplicates from Sorted List II
• Sort List
• Reverse Nodes in k-Group
• Remove Duplicates from Sorted List
• Remove Linked List Elements
• Partition List
• Delete the Middle Node of a Linked List
• Insertion Sort List
• Next Greater Node In Linked List
• Swapping Nodes in a Linked List
• Maximum Twin Sum of a Linked List
• Design Linked List
• Merge Nodes in Between Zeros
• Merge In Between Linked Lists
• Remove Zero Sum Consecutive Nodes from Linked List
• Reverse Nodes in Even Length Groups
• Linked List Components
• Double a Number Represented as a Linked List
• Valid Parentheses
• Min Stack
• Evaluate Reverse Polish Notation
• Next Greater Element (Circular)
• Largest Rectangle in Histogram
• Remove K Digits
• Minimum Remove to Make Valid Parentheses
• Decode String
• Asteroid Collision
• Simplify Path
• Basic Calculator
• Longest Valid Parentheses
• Sum of Subarray Minimums
• Next Greater Element I
• Final Prices With a Special Discount in a Shop
• Remove All Adjacent Duplicates in String
• Implement Queue using Stacks
• Minimum Add to Make Parentheses Valid
• 132 Pattern
• Remove Duplicate Letters
• Maximal Rectangle
• Exclusive Time of Functions
• Car Fleet
• Buildings With an Ocean View
• Backspace String Compare
• Baseball Game
• Number of Visible People in a Queue
• Sum of Subarray Ranges
• Maximum Width Ramp
• Remove Outermost Parentheses
• Maximum Nesting Depth of the Parentheses
• Design a Stack With Increment Operation
• Maximum Frequency Stack
• Score of Parentheses
• Using a Robot to Print the Lexicographically Smallest String
• Sliding Window Maximum
• Rotting Oranges (Multi-source BFS)
• Distance to Nearest Zero (01 Matrix)
• Open the Lock
• Number of Recent Calls
• Shortest Subarray With Sum at Least K
• Design Hit Counter
• Design Circular Queue
• Shortest Path in Binary Matrix
• Walls and Gates
• Longest Subarray With Absolute Diff ≤ Limit
• Bus Routes
• Moving Average from Data Stream
• Implement Stack using Queues
• First Unique Number
• Jump Game VII
• Shortest Path in a Grid with Obstacles Elimination
• Number of Students Unable to Eat Lunch
• Time Needed to Buy Tickets
• Dota2 Senate
• Snakes and Ladders
• Minimum Knight Moves
• The Maze
• Shortest Distance from All Buildings
• Minimum Genetic Mutation
• Shortest Path to Get All Keys
• Find the Safest Path in a Grid
• Continuous Subarrays
• Count Subarrays With Fixed Bounds
• Find Median from Data Stream
• Last Stone Weight
• IPO: Maximize Capital
• Single-Threaded CPU Scheduling
• Top K Frequent Words
• Sort Characters by Frequency
• Kth Smallest Element in a Sorted Matrix
• Furthest Building You Can Reach
• Maximum Number of Events That Can Be Attended
• Meeting Rooms III
• Minimum Number of Refueling Stops
• Smallest Range Covering Elements from K Lists
• Design Twitter
• Seat Reservation Manager
• Total Cost to Hire K Workers
• Process Tasks Using Servers
• Find K Pairs with Smallest Sums
• Ugly Number II
• Minimum Cost to Hire K Workers
• Maximum Performance of a Team
• Design A Leaderboard
• Exam Room
• K-th Smallest Prime Fraction
• Stock Price Fluctuation
• Design Task Manager
• Find Score of an Array After Marking All Elements
• Maximal Score After Applying K Operations
• Number of Orders in the Backlog
• Minimum Eating Speed
• Search Insert Position (Lower Bound)
• Capacity to Ship Packages Within D Days
• Find a Peak Element
• Split Array Largest Sum
• Median of Two Sorted Arrays
• Search a 2D Matrix
• Sqrt(x)
• Single Element in a Sorted Array
• Kth Missing Positive Number
• Find K Closest Elements
• Minimum Number of Days to Make m Bouquets
• Search a 2D Matrix II
• Peak Index in a Mountain Array
• Search in Rotated Sorted Array II
• Find the Smallest Divisor Given a Threshold
• Snapshot Array
• Valid Perfect Square
• Magnetic Force Between Two Balls
• H-Index II
• Find a Peak Element II
• Heaters
• Arranging Coins
• Maximum Candies Allocated to K Children
• Kth Smallest Number in Multiplication Table
• Find K-th Smallest Pair Distance
• Find Smallest Letter Greater Than Target
• Count Negative Numbers in a Sorted Matrix
• Successful Pairs of Spells and Potions
• Minimum Time to Complete Trips
• Minimized Maximum of Products Distributed to Any Store
• Minimum Speed to Arrive on Time
• Invert a Binary Tree
• Diameter of a Binary Tree
• Binary Tree Maximum Path Sum
• Construct a Tree From Preorder and Inorder
• House Robber III (Tree DP)
• Same Tree
• Symmetric Tree
• Subtree of Another Tree
• Binary Tree Zigzag Level Order Traversal
• Binary Tree Vertical Order Traversal
• All Nodes Distance K in Binary Tree
• Sum Root to Leaf Numbers
• Path Sum III
• Maximum Width of Binary Tree
• Flatten Binary Tree to Linked List
• Amount of Time for Binary Tree to Be Infected
• Boundary of Binary Tree
• Step-By-Step Directions From a Binary Tree Node to Another
• Vertical Order Traversal of a Binary Tree
• Count Good Nodes in Binary Tree
• Find Leaves of Binary Tree
• Binary Tree Cameras
• Binary Tree Paths
• Minimum Depth of Binary Tree
• Path Sum
• Count Complete Tree Nodes
• Create Binary Tree From Descriptions
• Count Nodes Equal to Average of Subtree
• Cousins in Binary Tree
• Maximum Difference Between Node and Ancestor
• Longest ZigZag Path in a Binary Tree
• Binary Tree Preorder Traversal
• Sum of Left Leaves
• Merge Two Binary Trees
• Find Largest Value in Each Tree Row
• Check Completeness of a Binary Tree
• Construct Binary Tree from Inorder and Postorder Traversal
• Maximum Level Sum of a Binary Tree
• Binary Tree Tilt
• Kth Smallest Element in a BST
• Range Sum of a BST
• Two Sum IV - Input is a BST
• Closest Binary Search Tree Value
• Trim a Binary Search Tree
• Inorder Successor in BST
• Recover Binary Search Tree
• Convert Sorted List to Binary Search Tree
• Convert BST to Greater Tree
• Minimum Absolute Difference in BST
• Closest Binary Search Tree Value II
• Balance a Binary Search Tree
• Unique Binary Search Trees
• Construct Binary Search Tree from Preorder Traversal
• Increasing Order Search Tree
• Find Mode in Binary Search Tree
• All Elements in Two Binary Search Trees
• Largest BST Subtree
• Count of Smaller Numbers After Self
• Two Sum BSTs
• Verify Preorder Sequence in Binary Search Tree
• Maximum Sum BST in Binary Tree
• Closest Nodes Queries in a Binary Search Tree
• Contains Duplicate III
• Number of Islands
• Network Delay Time
• Accounts Merge
• Number of Provinces (Connected Components)
• Redundant Connection
• Graph Valid Tree
• Word Ladder
• Cheapest Flights Within K Stops (Bellman–Ford)
• City With the Fewest Reachable Neighbors (Floyd–Warshall)
• Min Cost to Connect All Points (MST)
• Path With Minimum Effort (Dijkstra)
• Pacific Atlantic Water Flow
• Is Graph Bipartite?
• Course Schedule II
• Max Area of Island
• Flood Fill
• Surrounded Regions
• Number of Connected Components in an Undirected Graph
• Making A Large Island
• Reconstruct Itinerary
• Alien Dictionary
• Keys and Rooms
• Find Eventual Safe States
• Possible Bipartition
• Swim in Rising Water
• The Earliest Moment When Everyone Become Friends
• Parallel Courses III
• Number of Islands II
• Minimum Height Trees
• Find if Path Exists in Graph
• All Paths From Source to Target
• Most Stones Removed with Same Row or Column
• Critical Connections in a Network
• Shortest Bridge
• Reorder Routes to Make All Paths Lead to the City Zero
• Island Perimeter
• Detonate the Maximum Bombs
• Find All Possible Recipes from Given Supplies
• Parallel Courses
• Minimum Fuel Cost to Report to the Capital
• Detect Cycles in 2D Grid
• Find the Town Judge
• Minimize Malware Spread
• Count Unreachable Pairs of Nodes in an Undirected Graph
• Coin Change
• Longest Increasing Subsequence
• Word Break
• Edit Distance
• Climbing Stairs
• House Robber
• Decode Ways
• Unique Paths
• Minimum Path Sum
• Longest Common Subsequence
• 0/1 Knapsack
• Coin Change II (Unbounded Knapsack)
• Target Sum
• Matrix Chain Multiplication
• Burst Balloons
• Palindrome Partitioning II (Min Cuts)
• Best Time to Buy and Sell Stock With Cooldown
• Best Time to Buy and Sell Stock IV (k Transactions)
• Maximum Product Subarray
• Palindromic Substrings
• House Robber II
• Unique Paths II
• Maximal Square
• Interleaving String
• Regular Expression Matching
• Maximum Profit in Job Scheduling
• Longest Increasing Path in a Matrix
• Min Cost Climbing Stairs
• Pascal's Triangle
• Triangle
• Perfect Squares
• Minimum Cost For Tickets
• Predict the Winner
• Maximum Sum Circular Subarray
• Wildcard Matching
• Distinct Subsequences
• Russian Doll Envelopes
• Best Time to Buy and Sell Stock III
• Best Time to Buy and Sell Stock with Transaction Fee
• Combination Sum IV
• Number of Longest Increasing Subsequence
• Minimum Falling Path Sum
• Dungeon Game
• Frog Jump
• Integer Break
• Partition Array for Maximum Sum
• Minimum Difficulty of a Job Schedule
• Minimum Cost to Cut a Stick
• Count Square Submatrices with All Ones
• Domino and Tromino Tiling
• Cherry Pickup
• Longest String Chain
• Number of Ways to Form a Target String Given a Dictionary
• Painting the Walls
• New 21 Game
• Stone Game III
• Maximum Sum of 3 Non-Overlapping Subarrays
• Combinations
• Generate Parentheses
• Letter Combinations of a Phone Number
• Subsets II
• Combination Sum II
• Permutations II
• Palindrome Partitioning
• Restore IP Addresses
• Word Break II
• Expression Add Operators
• Subsets
• Combination Sum III
• Letter Case Permutation
• Matchsticks to Square
• Remove Invalid Parentheses
• Word Ladder II
• 24 Game
• Beautiful Arrangement
• Path with Maximum Gold
• Maximum Length of a Concatenated String with Unique Characters
• Generalized Abbreviation
• Factor Combinations
• Optimal Account Balancing
• Unique Paths III
• N-Queens II
• Different Ways to Add Parentheses
• The k-th Lexicographical String of All Happy Strings of Length n
• Shopping Offers
• Jump Game II (Minimum Jumps)
• Gas Station
• Partition Labels
• Fractional Knapsack
• Minimum Cost to Connect Sticks (Huffman)
• Candy
• Activity Selection (Max Meetings in One Room)
• Best Time to Buy and Sell Stock II
• Can Place Flowers
• Valid Parenthesis String
• Largest Number
• Boats to Save People
• Hand of Straights
• Maximum Swap
• Lemonade Change
• Assign Cookies
• Two City Scheduling
• Queue Reconstruction by Height
• Minimum Deletions to Make Character Frequencies Unique
• Maximum Units on a Truck
• Maximize Distance to Closest Person
• Reduce Array Size to The Half
• Wiggle Subsequence
• Bag of Tokens
• Minimum Number of Taps to Open to Water a Garden
• Broken Calculator
• Minimum Initial Energy to Finish Tasks
• Maximum Ice Cream Bars
• Maximum Element After Decreasing and Rearranging
• Minimum Number of Increments on Subarrays to Form a Target Array
• Move Pieces to Obtain a String
• Partitioning Into Minimum Number Of Deci-Binary Numbers
• Merge Overlapping Intervals
• Minimum Meeting Rooms
• Insert Interval
• Non-overlapping Intervals
• Car Pooling (Sweep Line)
• My Calendar I
• Summary Ranges
• Remove Covered Intervals
• My Calendar II
• Data Stream as Disjoint Intervals
• Minimum Interval to Include Each Query
• My Calendar III
• Video Stitching
• Missing Ranges
• Meeting Scheduler
• Count Days Without Meetings
• Range Module
• Divide Intervals Into Minimum Number of Groups
• Find Right Interval
• Minimum Time Difference
• The Skyline Problem
• Employee Free Time
• Brightest Position on Street
• Remove Interval
• Points That Intersect With Cars
• Implement a Trie (Prefix Tree)
• Design Add and Search Words (Wildcards)
• Search Suggestions (Autocomplete)
• Maximum XOR of Two Numbers
• Longest Word in Dictionary
• Map Sum Pairs
• Design Search Autocomplete System
• Concatenated Words
• Stream of Characters
• Palindrome Pairs
• Prefix and Suffix Search
• Implement Magic Dictionary
• Short Encoding of Words
• Sum of Prefix Scores of Strings
• Find the Length of the Longest Common Prefix
• Lexicographical Numbers
• Remove Sub-Folders from the Filesystem
• Words Within Two Edits of Dictionary
• Index Pairs of a String
• Count Prefix and Suffix Pairs
• Single Number (XOR)
• Counting Bits
• Power of Two
• Set Mismatch (Duplicate and Missing)
• Partition to K Equal Sum Subsets (Bitmask DP)
• Add Binary
• Single Number II
• Single Number III
• Bitwise AND of Numbers Range
• Total Hamming Distance
• Find the Difference
• Minimum Flips to Make a OR b Equal to c
• Gray Code
• Maximum Product of Word Lengths
• Divide Two Integers
• UTF-8 Validation
• Reverse Bits
• Number Complement
• Binary Watch
• Minimum Bit Flips to Convert Number
• Concatenation of Consecutive Binary Numbers
• Bitwise ORs of Subarrays
• Binary Gap
• Find Kth Bit in Nth Binary String
• XOR Queries of a Subarray
• Number of Steps to Reduce a Number to Zero
• Find The Original Array of Prefix Xor
• Count Primes (Sieve of Eratosthenes)
• Greatest Common Divisor of Strings
• Pow(x, n) — Fast Exponentiation
• Modular Exponentiation
• Binomial Coefficient nCr mod 10⁹+7
• Permutation Sequence (k-th Permutation)
• Nth Magical Number (LCM + Binary Search)
• Reservoir Sampling
• Palindrome Number
• Reverse Integer
• Roman to Integer
• Integer to Roman
• String to Integer (atoi)
• Multiply Strings
• Excel Sheet Column Title
• Fraction to Recurring Decimal
• Integer to English Words
• Angle Between Hands of a Clock
• Plus One
• Add Strings
• Fizz Buzz
• Count and Say
• Bulb Switcher
• Valid Number
• Max Points on a Line
• Robot Bounded In Circle
• Sequential Digits
• Power of Three
• Ugly Number
• Add Digits
• Perfect Number
• Sum of Square Numbers
• Rotate Function
• Count Good Numbers
• Number of Digit One
• Excel Sheet Column Number
• Nth Digit
• Factorial Trailing Zeroes
• Water and Jug Problem
• Nim Game
• The kth Factor of n
• Count Numbers with Unique Digits
• Rectangle Area
• Base 7
• Find the Closest Palindrome
• Design a Parking Lot
• Design a Vending Machine
• Design the Snake Game
• Design Connect Four
• Design a Chess Game
• Design a Deck of Cards for Blackjack
• Design Tic-Tac-Toe
• Design Splitwise
• Design a Meeting Room Scheduler
• Design a Text Editor with Undo and Redo
• Design a Spreadsheet with Formulas
• Design a Logging Framework
• Tell me about yourself
• Tell me about a conflict with a coworker
• Tell me about a time you failed
• Walk me through your most impactful project
• Tell me about a time you worked with ambiguity
• Tell me about critical feedback you received
• Tell me about a time you helped someone grow
• Why are you leaving your current role?
• What are you looking for in your next team?
• Tell me about a time you took ownership beyond your role
• Tell me about a problem you noticed that nobody else was addressing
• Tell me about a project you drove from idea to launch
• Tell me about a time you had to compromise
• Tell me about delivering a project across multiple teams
• Tell me about a time you led without formal authority
• Tell me about a time you convinced others to adopt your idea
• Tell me about a time you improved how your team works
• Tell me about working with an underperforming teammate
• Tell me about a decision you made with incomplete information
• Tell me about a difficult technical trade-off you made
• Tell me about a time you had to change direction mid-project
• Tell me about a time you had to cut scope
• Tell me about a mistake that affected others
• What is a weakness you're working on?
• Tell me about a production incident you handled
• Tell me about the hardest bug you've debugged
• Tell me about a time you had to learn something new quickly
• Tell me about a time you made the case for paying down tech debt
• What questions do you have for me?
• Tell me about a time you simplified something complex
• Tell me about a time you had to earn the trust of a skeptical team
• Tell me about a judgment call where others disagreed with you
• Tell me about something you learned outside your job that made you better at it
• Tell me about raising the bar when hiring or developing people
• Your team is split on a technical direction. What do you do?
• Tell me about a time you made sure every voice on your team was heard
• Tell me about a time you advocated for users
• Tell me about a time you kept going on a problem that seemed stuck
• Tell me about a time you changed your mind
• Tell me about a time you made someone feel they belonged
• Teach me something you recently learned