285 Algorithm questions that open without a paid plan — full statement, editor and judged verdict. Easiest first.
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| Question | Company | Difficulty | Reported |
|---|---|---|---|
| Valid Parentheses | Apple / Amazon / Bloomberg / Boston Consulting Group / ByteDance / Intuit / LinkedIn / Meta / NVIDIA / Oracle / Pinduoduo / Snowflake / Walmart Labs / WeRide | Easy | Feb 07, 2026 |
| Longest Substring Without Repeating Characters II | Apple / Amazon / Bloomberg / ByteDance / Datadog / Meta / Microsoft / NVIDIA / Pinduoduo / Snapchat | Easy | Mar 06, 2026 |
| Best Time to Buy and Sell Stock II | Apple / Amazon / Bloomberg / ByteDance / Citadel / Google / Meta / Microsoft / Uber | Easy | Mar 09, 2026 |
| Lowest Common Ancestor of a Binary Tree | Uber / Amazon / Atlassian / ByteDance / Google / Meta / Microsoft / PayPal / Unknown | Easy | Feb 26, 2026 |
| In-Flight Movie Pair (Two Sum Variant) | Amazon / Bloomberg / ByteDance / Ebay / Goldman Sachs / Meta / WeRide | Easy | Mar 17, 2026 |
| Maximum Subarray | Apple / Amazon / Atlassian / ByteDance / Cisco / PayPal / Squarepoint | Easy | — |
| Remove Duplicates from Sorted Array | Meta / Microsoft / NVIDIA / Upstart | Easy | — |
| Hash Map Counting / Lookup Problem | Microsoft / Ebay / Visa | Easy | — |
| Matrix Multiplication | Microsoft / GEICO / WeRide | Easy | — |
| Palindrome Detection | Citadel / Amazon / Boston Consulting Group | Easy | — |
| Check Prefix Permutation | Uber / Microsoft | Easy | Feb 02, 2026 |
| Contains Duplicate II | Netflix / Google | Easy | — |
| Convert Snake Case to Camel Case | Ramp / Ebay | Easy | Apr 2025 |
| Final Prices With a Special Discount in a Shop | Uber / Microsoft | Easy | Apr 01, 2026 |
| Generate 2D Minesweeper Grid | Uber / Block | Easy | May 2026 |
| Implement Softmax | Luma AI / Amazon | Easy | — |
| Look-and-Say Sequence | Intuit / Cisco | Easy | Sep 29, 2025 |
| Palindrome String Check (Handle Empty and Null) | Arista / Boston Consulting Group | Easy | — |
| Remove Duplicates from Sorted Linked List | ByteDance / Rubrik | Easy | — |
| Segregate Binary String (Move Ones to End) | Akuna Capital / Google | Easy | Aug 26, 2025 |
| Add sorting to a comment list with persistence across refresh | Bobyard | Easy | — |
| Add Two Reversed Digit Lists | Cisco | Easy | Sep 06, 2025 |
| Alphanumeric Vowel / Consonant Count | JPMorgan | Easy | Jun 30, 2025 |
| Alternating String Merge | Cisco | Easy | Sep 04, 2025 |
| Anagram Queries on Word List | Goldman Sachs | Easy | Oct 26, 2024 |
| Analyze Vehicle JSON Log | Applied Intuition | Easy | — |
| Auto Email Generation | Roblox | Easy | Sep 02, 2025 |
| C++ only, ~10 min | Shopify | Easy | Aug 29, 2025 |
| Calculate and Sort Customer Ratings | Atlassian | Easy | — |
| Calculate Fibonacci Number | Snowflake | Easy | — |
| Card Game Gem Affordability and Discount Calculation Functions | Brex | Easy | — |
| Chairs / Restaurant Order Simulation | Goldman Sachs | Easy | Oct 26, 2024 |
| Check Validity of Input String | Snowflake | Easy | — |
| Compliance Alert / Trailing-Average Sliding Window | Goldman Sachs | Easy | Oct 26, 2024 |
| Compress Consecutive Ranges | Cisco | Easy | Aug 26, 2025 |
| Convert a Column Number to an Excel-Style Label | Houzz | Easy | 🆕 Sep 18, 2026 |
| Count Unique Pairs With Difference K | Goldman Sachs | Easy | Oct 26, 2024 |
| Count Value Occurrences in a Binary Tree | Apple | Easy | Dec 10, 2025 |
| Delete-One-Character Positions | JPMorgan | Easy | Jul 29, 2025 |
| Ethernet Cable Square Count | Goldman Sachs | Easy | Sep 22, 2025 |
| File Profiler | Anthropic | Easy | — |
| Find Combinations After Flip | Uber | Easy | — |
| Find Destination Node | Yelp | Easy | Apr 20, 2025 |
| Find Failed Login IPs | Apple | Easy | Nov 20, 2025 |
| Find Index of Max Rate to Price Ratio | Uber | Easy | — |
| Find Middle Course | Robinhood | Easy | Apr 10, 2025 |
| Find Out Prime or Composite | Cisco | Easy | — |
| Find Path in Fibonacci Tree | Databricks | Easy | Apr 01, 2026 |
| Find Target with Rotation | Uber | Easy | — |
| Graph Traversal using BFS/DFS | PayPal | Easy | — |
| Grasshopper Problem | Squarepoint | Easy | — |
| Implement a Coroutine Step by Step | Hudson River Trading | Easy | — |
| Implement Unix uniq | Vanta | Easy | — |
| Interleave Three Equal-Length Strings | Upstart | Easy | — |
| IP CIDR Range Query | Databricks | Easy | — |
| Jaccard Business Similarity | Yelp | Easy | Apr 20, 2025 |
| Linked List Binary to Decimal | Cisco | Easy | Sep 06, 2025 |
| Longest Substring of All Same Letter | Goldman Sachs | Easy | Nov 21, 2024 |
| Maximum Drop Points in One Line | Cisco | Easy | Jul 17, 2025 |
| Merge Two Sorted Vectors | Squarepoint | Easy | — |
| Minimize Shopping Department Visits | Atlassian | Easy | Jul 03, 2025 |
| Minimum Swaps for Even / Odd Partition | Cisco | Easy | Sep 04, 2025 |
| Paint Line and Count Adjacent Same Colors | Uber | Easy | — |
| Parse String | Applied Intuition | Easy | — |
| Row Maximum / Column Minimum | Cisco | Easy | Sep 04, 2025 |
| Ruby only, ~10 min | Shopify | Easy | Aug 29, 2025 |
| Second-Smallest Unique Element | Goldman Sachs | Easy | Nov 14, 2024 |
| Simple TypeScript Program | Snowflake | Easy | — |
| Sliding Window Problem | Faire | Easy | — |
| Social Network Likes Count | Lead Bank | Easy | — |
| Social Network Recommendation | Lead Bank | Easy | — |
| Sort Colors and Sizes | Pinduoduo | Easy | — |
| Sort Dictionary Keys | Netflix | Easy | — |
| Split Array: Left Sum Greater | JPMorgan | Easy | Sep 05, 2025 |
| String Shift | Rubrik | Easy | — |
| Merge Intervals | Apple / Amazon / ByteDance / Google / Lyft / Meta / Microsoft / Netflix / NVIDIA / OpenAI / Optiver / Rippling / Roblox / Snowflake / Two Sigma / Uber | Medium | Feb 04, 2026 |
| Minimum Meeting Rooms | Ramp / Amazon / Bloomberg / ByteDance / Ebay / Google / IBM / Meta / Microsoft / Roblox / Snowflake / Uber / Walmart Labs | Medium | — |
| Course Schedule | Apple / Amazon / ByteDance / DoorDash / Google / Meta / Netflix / Snapchat / Snowflake / Uber | Medium | Mar 20, 2026 |
| Basic Calculator | Netflix / ByteDance / Google / Instacart / Meta / Microsoft / Snapchat / SoFi / Uber | Medium | Jan 30, 2026 |
| Best Time to Buy and Sell Stock IV | Meta / Amazon / Apple / Bloomberg / Goldman Sachs / Lyft / Microsoft / Point72 | Medium | — |
| Number of Islands (Plain and Streaming) | Uber / Amazon / Bloomberg / ByteDance / Google / LinkedIn / Microsoft / Snapchat | Medium | Apr 09, 2026 |
| Group Anagrams | Uber / Amazon / Apple / Databricks / Meta / OKX / Roblox | Medium | — |
| Search from the end in a sorted array (variant) | Snapchat / ByteDance / Google / Meta / Pinduoduo / Rokt / Walmart Labs | Medium | — |
| Time Based Key-Value Store | Uber / Amazon / ByteDance / Gusto / Microsoft / Oracle | Medium | Mar 20, 2026 |
| Distributed Rate Limiter | xAI / Atlassian / Expedia / LinkedIn / Snowflake | Medium | Apr 01, 2026 |
| Merge K Sorted Lists | Apple / ByteDance / Citadel / Meta / Snowflake | Medium | Apr 01, 2026 |
| Product of Array Except Self | Apple / Amazon / GEICO / Microsoft / Squarepoint | Medium | Apr 02, 2026 |
| Sliding-Window Rate Limiter II | Roblox / Atlassian / Okta / Ramp / Snapchat | Medium | May 2026 |
| Implement Power Function | ByteDance / LinkedIn / NVIDIA / WeRide | Medium | — |
| Koko Eating Bananas | Apple / Amazon / DoorDash / Optiver | Medium | Apr 14, 2026 |
| Rotate a Matrix by 90 Degrees In Place | Apple / Amazon / Cisco / Uber | Medium | May 2026 |
| Count Palindromic Substrings | Goldman Sachs / Citadel / Voleon | Medium | Oct 26, 2024 |
| Evaluate String Expression | Google / Affirm / Uber | Medium | Jun 10, 2026 |
| House Robber Series | Databricks / Amazon / Expedia | Medium | Nov 18, 2025 |
| Jump Game | ByteDance / Microsoft / Visa | Medium | — |
| Minimal Operations | Salesforce / Akuna Capital / Palantir | Medium | — |
| Minimum Operations to Reduce an Integer to 0 | Uber / Google / Salesforce | Medium | Apr 01, 2026 |
| Restore Valid IPv4 Addresses | OpenAI / ByteDance / OKX | Medium | — |
| Shortest Bridge | Uber / Apple / Tesla | Medium | Feb 21, 2026 |
| Simplify Expression | Oracle / Google / Meta | Medium | Jun 10, 2025 |
| Token Bucket Rate Limiter II | Uber / Dropbox / Meta | Medium | — |
| First Missing Positive | Netflix / Goldman Sachs | Medium | Mar 11, 2026 |
| Infection Spread Simulation | OpenAI / Anthropic | Medium | Jun 19, 2026 |
| Intersection of Two Linked Lists | Apple / LinkedIn | Medium | Mar 02, 2026 |
| Maximize Pipeline Throughput | Uber / Snowflake | Medium | Jun 04, 2026 |
| Minimum Knight Moves | Uber / Salesforce | Medium | Mar 28, 2026 |
| Minimum Swaps to Sort (Cycle Decomposition) | Akuna Capital / JPMorgan | Medium | Dec 20, 2025 |
| Spiral Matrix Traversal | Goldman Sachs / Microsoft | Medium | Nov 15, 2024 |
| String to Integer (atoi) | Netflix / Bloomberg | Medium | Mar 03, 2026 |
| Swap Parity | Palantir / SoFi | Medium | — |
| 1-D Valid Convolution with Multithreading Follow-up | IBM | Medium | Aug 13, 2025 |
| Anagram Sentence Substitutions | SoFi | Medium | Sep 25, 2025 |
| Array Challenge: Left-Comparison Running Counter | Akuna Capital | Medium | Sep 24, 2025 |
| Batch and Pad Variable-Length Vectors with Optional Final-Batch Dropping | Siemens | Medium | 🆕 Sep 04, 2026 |
| Binary Search Tree Pruning | PayPal | Medium | — |
| Binary Search — Rightmost Index of Duplicate | Oracle | Medium | Jul 07, 2025 |
| Build Naive Bayes spam classifier with F1 | Disney | Medium | Nov 01, 2025 |
| Campground Carpool | Atlassian | Medium | Jul 03, 2025 |
| Cell Simulation / Conway's Game of Life | OpenAI | Medium | — |
| Check Vertical Reflection Symmetry with Duplicate Points | Nuro | Medium | Feb 15, 2026 |
| Choose container set to minimize waste | Imc | Medium | Oct 06, 2025 |
| Circular Active Computers Window | JPMorgan | Medium | Jul 29, 2025 |
| Citation Highlighting | Harvey | Medium | Aug 09, 2026 |
| Cloud Storage System | Ramp | Medium | Aug 2025 |
| Connect Four Game Evaluation | Snowflake | Medium | — |
| Contains Duplicate III | Netflix | Medium | May 26, 2026 |
| Count 3^x * 5^y Numbers and Decreasing Subarrays | IBM | Medium | Apr 25, 2026 |
| Count Alert Triggers | Yelp | Medium | Apr 21, 2025 |
| Cows and Bulls (Guess the Number) | Shopify | Medium | Jun 19, 2025 |
| Decode Ways / Alphanumeric Combination | Goldman Sachs | Medium | Jul 11, 2025 |
| Dependency Cycle Detection (Deadlock) | Okta | Medium | Nov 05, 2025 |
| Deployments Node Calculation | Snowflake | Medium | — |
| Determine if a Binary Tree is Perfect | Snowflake | Medium | — |
| Determine Valid Build Order | Airtable | Medium | — |
| Dictionary Encoding (Lossless) for Comma-Separated Words | Amplitude | Medium | — |
| Dictionary Word Transformation Path | Medium | Jul 21, 2025 | |
| DNA Substring Palindrome Cost Sum | Intuit | Medium | Dec 25, 2025 |
| Dojo Pythonic Coding Pair: Permutation Check and Pow | Tesla | Medium | Jul 25, 2025 |
| Dynamic programming, ~45 min, any language | Shopify | Medium | Aug 29, 2025 |
| Earliest Coordinate Reach with Optional Moves | IBM | Medium | Sep 09, 2025 |
| Efficient Text Search with Proximity Constraint | Palantir | Medium | — |
| Encyclopedia Removal Grid | Goldman Sachs | Medium | Sep 08, 2025 |
| Equalize Letter Frequencies With Add / Remove | Goldman Sachs | Medium | Sep 10, 2025 |
| Evaluate a Boolean Formula AST | Sigmacomputing | Medium | — |
| Fairly Distribute Money With Limits | Gusto | Medium | — |
| Filter nested comments and keep only matched nodes and their descendants | Bobyard | Medium | — |
| Find accessible devices via nested memberships | Axon | Medium | Mar 01, 2026 |
| Find All Dependencies | Vanta | Medium | — |
| Find Clients Outside Provider Coverage | Oscar Health | Medium | — |
| Find k-th recipient in command propagation order | Imc | Medium | Dec 15, 2025 |
| Find Last Cell | Cisco | Medium | — |
| Find Maximum Number of Strings | Moveworks | Medium | — |
| Find Minimum Score Threshold | Roblox | Medium | Sep 02, 2025 |
| Find Missing and Repeated Element | Akuna Capital | Medium | Sep 23, 2025 |
| Find Number of Joins in an Array | Uber | Medium | — |
| Find the Intersection of Two Linked Chains | C3 AI | Medium | Aug 15, 2026 |
| Find the Largest K Elements with Partitioning | AMD | Medium | 🆕 Sep 14, 2026 |
| Find Unique Number in Consecutive Pairs | Snowflake | Medium | — |
| Flip and Compare in Arrays | Uber | Medium | — |
| Fractional Inventory | Robinhood | Medium | Apr 23, 2026 |
| Generate All Valid Combinations of Balanced Parentheses | Disney | Medium | Mar 27, 2026 |
| Generate Unique Usernames | Squarepoint | Medium | — |
| Get Minimum Operations to Sort Array | Moveworks | Medium | — |
| Graph Coloring Problem | WeRide | Medium | — |
| Guess Number | Airbnb | Medium | Sep 24, 2025 |
| Hash a Repository with a Merkle Tree and Find Changed Files | Cursor | Medium | Apr 07, 2026 |
Implement uniq — Unique Lines in a File |
Vanta | Medium | Jul 16, 2026 |
| Implement a Card-Details Form with Dependent Validation | Cohere | Medium | 🆕 Sep 15, 2026 |
| Implement popup and redirect in JavaScript | Bitkernel | Medium | Oct 03, 2025 |
| Implement Trie with Non-Standard Alphabet | Snowflake | Medium | — |
| Knockout Tournament Match Counts | Drw | Medium | Oct 08, 2025 |
| Line by Line Document Generator | Squarepoint | Medium | — |
| Linear Interpolation | Two Sigma | Medium | May 10, 2026 |
| Load Factor Calculation | Robinhood | Medium | Mar 2026 |
| Log Parser with Multi-Line Follow-up | Oracle | Medium | Aug 06, 2025 |
| Longest Diagonal Pattern | Uber | Medium | — |
| Longest Subarray With Sum ≤ K | Goldman Sachs | Medium | Oct 26, 2024 |
| Matrix Zig-Zag Traversal | Cisco | Medium | Aug 25, 2025 |
| Max Distinct Counts After Splitting Array | IBM | Medium | Jul 09, 2025 |
| Max Harvested Crops | Hudson River Trading | Medium | — |
| Maximize Score Sum | Uber | Medium | — |
| Maximum Completable Tasks with Prerequisites (Topological) | Oracle | Medium | Apr 02, 2025 |
| Maximum Non-Adjacent Chocolates | Cisco | Medium | Jul 17, 2025 |
| Meeting Rooms Allocation with Delay | Uber | Medium | — |
| Merge Common Substring | Yelp | Medium | Apr 20, 2025 |
| Merge K Sorted Lists (incl. K = 3) | Goldman Sachs | Medium | Jun 09, 2025 |
| Mike and Gems | Rubrik | Medium | — |
| Min Remove to Make Valid Parentheses | Meta | Medium | Apr 01, 2026 |
| Min × Max Product After Push / Pop | Goldman Sachs | Medium | Oct 26, 2024 |
| Minimum Hits Needed | IBM | Medium | — |
| Minimum Insertions / Deletions Password Update | Cisco | Medium | Sep 06, 2025 |
| Minimum Link Reallocation to Connect Repositories | IBM | Medium | Sep 21, 2025 |
| Minimum Machines for Task Scheduling | Expedia | Medium | — |
| Minimum Number of Umbrellas | Squarepoint | Medium | — |
| Minimum Removal Rounds by Smallest Response Time | IBM | Medium | Jul 09, 2025 |
| Minimum Total Cost for Image Filters | WeRide | Medium | — |
| Minimum Value Weight | Snowflake | Medium | — |
| Minimum Vertices to Traverse Directed Graph | Airbnb | Medium | Sep 17, 2025 |
| Mining Block | Coinbase | Medium | May 05, 2026 |
| Moderator List Hierarchy | Medium | Jun 23, 2026 | |
| Morse Code Conversion | Oscar Health | Medium | — |
| Nested Structure Flatten and Unflatten | xAI | Medium | Feb 26, 2026 |
| Number of Unique Binary Trees | PayPal | Medium | — |
| Optimal Crop Selection for Maximum Profit | Block | Medium | — |
| Paint House | Shopify | Medium | Aug 29, 2025 |
| Payment Invoice Reconciliation | Stripe | Medium | May 12, 2026 |
| Pivot Table Profit Analyzer | Instacart | Medium | Jul 30, 2025 |
| Plus-Multiply Even / Odd Parity | Goldman Sachs | Medium | Oct 26, 2024 |
| Prefix Search I | Yelp | Medium | Apr 20, 2025 |
| Process Starvation Time | Goldman Sachs | Medium | Sep 22, 2025 |
| Random User Pairing | Yelp | Medium | Apr 20, 2025 |
| Randomly Partition Array | Roblox | Medium | Sep 03, 2025 |
| Rate Limiter by IP Address | Ramp | Medium | Sep 29, 2025 |
| Remove Read-Only Files | Datadog | Medium | — |
| Rotate Matrix with Gravity Effect | Uber | Medium | — |
| Round Price to Nearest Valid Tick | Akuna Capital | Medium | Sep 22, 2025 |
| Round-Trip Mission Schedule | Uber | Medium | Jul 10, 2025 |
| Route Curve Simplification Function | Applied Intuition | Medium | — |
| Route Nearest Checkpoint | Tesla | Medium | Aug 11, 2025 |
| Same Word of HTML Labels | Roblox | Medium | Sep 04, 2025 |
| Sentence Variations with Anagram | Squarepoint | Medium | — |
| Shipping Cost Calculator | Stripe | Medium | Dec 19, 2025 |
| Simple Moving Average over a Fixed-Size Sliding Window | Chicago Trading | Medium | — |
| Simulate Stack | Rubrik | Medium | — |
| Sliding-Window Rate Limiter / Abuse IP Detection | IBM | Medium | Sep 09, 2025 |
| Split a Chunked Text Stream into Line-Balanced Parts | Together AI | Medium | 🆕 Sep 15, 2026 |
| Stack Trace Reconstruction | Anthropic | Medium | Jun 04, 2026 |
| Task Query by Time and Name Filter with Sorting | Circle | Medium | — |
| Top Love Message Receivers | Yelp | Medium | Apr 20, 2025 |
| Toy Language | OpenAI | Medium | — |
| Track Customer Website Visits | Uber | Medium | — |
| Unequal Elements | Snowflake | Medium | Jul 20, 2025 |
| User Flight Location Tracker | Ramp | Medium | Jun 01, 2026 |
| Valid Triangle + Point Inclusion | Goldman Sachs | Medium | Oct 26, 2024 |
| Validate Playlist Sequence | Roblox | Medium | Sep 02, 2025 |
| Vowels Substring | Snowflake | Medium | Jul 20, 2025 |
| Web Crawler | Anthropic | Medium | May 03, 2026 |
| Word Pattern / Meta-Pattern Match (Backtracking) | Vanta | Medium | Dec 04, 2024 |
| Word Search in Rows and Columns | Cisco | Medium | Jul 17, 2025 |
| Trapping Rain Water | Apple / Amazon / Bloomberg / ByteDance / Goldman Sachs / Meta / Squarepoint / Tradedesk | Hard | Apr 01, 2026 |
| Closest Pair of Points | Citadel / Luma AI | Hard | Jan 05, 2026 |
| Count Paths That Can Form a Palindrome in a Tree | Uber / Google | Hard | Mar 22, 2026 |
| IPO Share Allocation | Two Sigma / Point72 | Hard | Mar 25, 2026 |
| Largest Rectangle in Histogram | ByteDance / Airwallex | Hard | Jan 29, 2026 |
| Transformer Attention Mask and Heads Coding | Apple / Scale AI | Hard | Jun 16, 2026 |
| 1D Players and Watcher With Direction Changes | Hudson River Trading | Hard | — |
| Alien Dictionary Evaluation | Uber | Hard | — |
| Bottom-Insertion Connect Game: Detect the First k-in-a-Row Winner | Jane Street | Hard | Nov 06, 2025 |
| Code Review: Thread Safety of a Python Compute-and-Cache Function | Mercor | Hard | May 01, 2026 |
| Compute Remaining GPUs With Switching Limits | Mistral AI | Hard | Apr 16, 2026 |
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