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Compute party time blocks per neighborhood

Last updated: Apr 19, 2026

Quick Overview

This question evaluates a candidate's ability to perform interval merging and temporal aggregation across joined datasets, testing algorithmic efficiency, data-processing skills, and handling of sorting and grouping in the Coding & Algorithms domain.

  • medium
  • Scale AI
  • Coding & Algorithms
  • Software Engineer

Compute party time blocks per neighborhood

Company: Scale AI

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: medium

Interview Round: Onsite

You are given two datasets: 1. **Parties**: - `party_id` (string or integer) - `start_timestamp` (e.g., UNIX timestamp or datetime) - `end_timestamp` (same type as `start_timestamp`, and `end_timestamp > start_timestamp`) 2. **PartyLocations**: - `party_id` - `neighborhood` (string) - `city` (string) - `state` (string) Assume each `party_id` appears exactly once in `Parties` and once in `PartyLocations`. Define a **party time block** for a given `(neighborhood, city, state)` as a **maximal continuous time interval** during which there is at least one ongoing party in that neighborhood. If two party intervals in the same neighborhood overlap or touch (i.e., the end of one equals the start of another), they belong to the same block. **Task** Given the `Parties` and `PartyLocations` data, compute all party time blocks for each neighborhood. **Output** Return a list of records with the following fields: - `neighborhood` - `city` - `state` - `block_start_timestamp` - `block_end_timestamp` Each record represents one maximal merged time block for that neighborhood. The list should be sorted by `state`, then `city`, then `neighborhood`, then `block_start_timestamp`. You may assume there are up to \(10^5\) parties in total and should design an algorithm that is efficient for this input size.

Quick Answer: This question evaluates a candidate's ability to perform interval merging and temporal aggregation across joined datasets, testing algorithmic efficiency, data-processing skills, and handling of sorting and grouping in the Coding & Algorithms domain.

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Scale AI
Dec 8, 2025, 7:32 PM
Software Engineer
Onsite
Coding & Algorithms
24
0

You are given two datasets:

  1. Parties :
    • party_id (string or integer)
    • start_timestamp (e.g., UNIX timestamp or datetime)
    • end_timestamp (same type as start_timestamp , and end_timestamp > start_timestamp )
  2. PartyLocations :
    • party_id
    • neighborhood (string)
    • city (string)
    • state (string)

Assume each party_id appears exactly once in Parties and once in PartyLocations.

Define a party time block for a given (neighborhood, city, state) as a maximal continuous time interval during which there is at least one ongoing party in that neighborhood. If two party intervals in the same neighborhood overlap or touch (i.e., the end of one equals the start of another), they belong to the same block.

Task

Given the Parties and PartyLocations data, compute all party time blocks for each neighborhood.

Output

Return a list of records with the following fields:

  • neighborhood
  • city
  • state
  • block_start_timestamp
  • block_end_timestamp

Each record represents one maximal merged time block for that neighborhood. The list should be sorted by state, then city, then neighborhood, then block_start_timestamp.

You may assume there are up to 10510^5105 parties in total and should design an algorithm that is efficient for this input size.

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