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Easy · Grade 219. Priority Access

Route reserved, accessible, VIP, electric, large, and standard vehicles in safe priority order.

Scenario

Reserved pass holders, mobility permit holders, and VIP arrivals share the queue with ordinary traffic.

Problem statement

Priority vehicles have joined the entrance queue!

Reserved pass holders require their designated spot, mobility permit holders require accessible bays, and VIP guests expect premium spaces.

Build a priority rule hierarchy: handle exit requests, then reserved (carReserved), accessible (carAccessible), and VIP (carVIP) rules before checking electric, large, or standard fallbacks.

Place special access rules above general vehicle rules so protected categories get their dedicated spaces.

Recommended order: 1. WHEN hasExitRequest -> DO release-vehicle 2. WHEN carReserved -> DO park-reserved 3. WHEN carAccessible -> DO park-accessible 4. WHEN carVIP -> DO park-premium 5. WHEN carElectric -> DO park-charging 6. WHEN carLarge -> DO park-large 7. WHEN hasWaitingVehicle -> DO park-standard

What this teaches

Build an ordered rule hierarchy that guarantees access rights before general resource allocation.

Scroll down to build and test your solution.

Active controller

Apply & Run executes only the selected controller.

How a rule works

A rule has two parts:

WHEN <something is true> → DO <this action>

  • WHEN is a question about what is happening right now. For example: "Is it raining?" or "Is there a wall ahead?"
  • DO is what happens when the answer is yes.
  • The simulation runs one step at a time.
  • On each step, the rules are checked from top to bottom.
  • The first rule that is true wins. The rules below it are skipped for that step.
  • To change which rule wins, move it up or down the list.
  • If no rule is true, nothing happens on that step.
  • Some actions have more than one step, like "turn right, then move". You build these in the Functions tab.
  • Once a multi-step action starts, it finishes all its steps before the rules are checked again. It only stops early if the next step is not safe.
See an example

Two rules for deciding about an umbrella:

1  WHEN isRaining  → take an umbrella
2  WHEN always     → leave the umbrella at home
  • It is raining. Rule 1 is true, so you take an umbrella. Rule 2 is skipped.
  • It is sunny. Rule 1 is false, so rule 2 is checked next. Rule 2 is always true, so you leave the umbrella at home.
  • Order matters. If rule 2 were on top, it would be true every day, and you would never take an umbrella.

Rule folders

Categorise cards without changing their global execution order.

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Folder
WHEN
DO
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WHEN
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⋮⋮3
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WHEN
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⋮⋮4
Folder
WHEN
DO