How should I practice Park Train Cars by Preference?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Mercor onsite interview problems in FastPrep.

Is Park Train Cars by Preference associated with Mercor?

FastPrep tags this as a Mercor onsite interview coding practice problem when the problem catalog has that company and stage context.

Park Train Cars by Preference

Mercor● MediumFULLTIMEONSITE INTERVIEW

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Problem statement

A rail yard has parking spots numbered from 0 through spotCount - 1. Train car i may be parked in any spot listed in preferences[i].

Each spot may hold at most one car. Return whether every train car can be assigned to an acceptable spot. Cars may be reassigned from an earlier choice while searching for a complete placement.

Function

canParkTrain(spotCount: int, preferences: int[][]) → boolean

Examples

Example 1

spotCount = 3preferences = [[0,1],[1],[1,2]]return = true

The cars can use spots 0, 1, and 2 respectively.

Example 2

spotCount = 2preferences = [[0],[0]]return = false

Both cars require the same single spot, so one remains unparked.

Example 3

spotCount = 4preferences = [[0,1],[0,2],[1,3],[2,3]]return = true

Reassigning an earlier car exposes a complete placement.

Constraints

1 <= preferences.length, spotCount <= 200
Each preference list is nonempty and contains distinct valid spot indices.
A car occupies exactly one spot and a spot holds at most one car.