Filter ads by a single rule

Single-Rule Ad Filter

Context

When a user watches content, the system needs to filter an ad pool to find ads that match one rule. Implement a lightweight filter that supports a single rule with an operator.

Data model

Ad

• id: String
• targetLocations: Set<String> (e.g., { "CA", "TX" } )
• age: int (intended viewer age for the ad)

Rule

• targetLocations: Set<String> (optional)
• minAge: Integer (optional)
• maxAge: Integer (optional)
• operator: "AND" | "OR"

Matching semantics

• Location match : if rule.targetLocations is present and non-empty, then an ad matches the location constraint if rule.targetLocations ⊆ ad.targetLocations (i.e., the ad targets all locations required by the rule).
• Age match :
  • if rule.minAge is present, require ad.age >= rule.minAge
  • if rule.maxAge is present, require ad.age <= rule.maxAge
• Combine the (present) constraints using rule.operator :
  • AND : ad must satisfy all present constraints
  • OR : ad must satisfy at least one present constraint
• If a constraint is absent, ignore it.

Input / Output

• Input : List<Ad> ads , Rule rule
• Output : List<String> of matching ad.id values, preserving the original input order

Example

Rule: minAge = 21, targetLocations = {"US"}, operator = AND

Ads:

• A : age=21 , targetLocations={"US","CA"} → match
• B : age=13 , targetLocations={"US"} → no (age)
• C : age=25 , targetLocations={"CA"} → no (location)

Output: ["A"]

Constraints (assume)

• ads.length can be large; keep it efficient.
• Location strings may vary in case; clarify/handle consistently (e.g., normalize to upper-case) if needed.