Design Support Ticket RoutereasyDesign Support Ticket Router
A support desk sends each ticket through a chain of handlers. A specialist accepts tickets in its own category. If it cannot accept a ticket, it passes the ticket to the next handler. The first handler that accepts the ticket returns the response and stops the chain.
The provided SupportDesk exposes this API:
SupportDesk()creates a desk with an empty chain.boolean addHandler(String kind)appends"billing","technical"or"general"to the end of the chain. It returnsfalsefor an unknown kind or a kind already present.String chainOrder()returns handler names from head to tail joined by" -> ", or"EMPTY".String route(String category, String subject)sends a ticket into the chain. A successful response is"<HandlerName>: <subject>". If no handler accepts it, return"UNHANDLED". A category other than"billing","technical"or"general"returns"INVALID"without entering the chain.int handlerCount()returns the number of handlers in the chain.int handledCount()returns the number of tickets successfully handled across allroutecalls.
The handlers are:
BillingSupportaccepts only"billing"tickets.TechnicalSupportaccepts only"technical"tickets.GeneralSupportaccepts every valid ticket, making it a fallback when it appears late in the chain and a catch-all when it appears early.
Complete only the five Chain of Responsibility types left in the starter code:
SupportHandlerdefinesname,setNext,getNextandhandle.BaseSupportHandlerstores the next handler and centralises forwarding. When there is no next handler, forwarding returns"UNHANDLED".BillingSupport,TechnicalSupportandGeneralSupportimplement the acceptance rules above.
The supplied desk builds and reports the chain, validates categories, and counts successful routes. SupportDesk is the only type the tests call; do not change it.
Example 1:
Input:
Output:
Explanation: Billing support declines and forwards the ticket. Technical support accepts it and returns immediately, so general support is not reached.
Example 2:
Input:
Output:
Explanation: General support is first and accepts every valid category. The billing handler behind it never sees either ticket.
Constraints
1 <= subject.length <= 80- At most
3handlers are added to one chain. - At most
100calls in total are made across all methods.
How the design is graded
needs 7/10 to pass- Chain separation
Full marks when billing, technical and general support are separate handler classes behind one contract, each handler owns its matching rule, and `route` starts at the head without comparing categories. Lose points heavily when the desk uses conditionals to choose a handler directly or walks the chain and performs the matching itself.
- First match stops the chain
Full marks when a specialist forwards only tickets it cannot accept, the general handler accepts every valid ticket, and no handler forwards after producing a response. Lose points when several handlers answer one ticket or when a specialist drops a ticket it cannot handle.
- Structure and edge cases
Full marks when handlers are appended in insertion order, unknown and repeated kinds are rejected without changing the chain, an empty chain returns `UNHANDLED`, invalid categories return `INVALID`, and only successful routes increase `handledCount`. Lose points for printing to stdout.
Passing every test is not enough on its own. A submission is accepted only when the design also clears the bar.
| Call | Returns |
|---|---|
| new SupportDesk() | null |
| addHandler("billing") | true |
| addHandler("technical") | true |
| addHandler("general") | true |
| chainOrder() | "BillingSupport -> TechnicalSupport -> GeneralSupport" |
| route("technical", "Cannot connect to Wi-Fi") | "TechnicalSupport: Cannot connect to Wi-Fi" |
| handledCount() | 1 |
Billing support declines the technical ticket and forwards it. Technical support accepts it, so general support is never called.
Run checks these cases. Submit also runs a larger hidden set.