FA-96733 / Phone number formatting / Member archive

Number list range compression: the tail is always two digits · case 03

"5550198-5550201" is emitted as "5550198-01".

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input a list of digit strings. Deduplicate and sort by (length, text). Consecutive numbers of equal length (each one greater than the previous) form a run. A run of one is emitted as is; a longer run is emitted as START-TAIL where TAIL is END without the prefix it shares with START.

Why this case matters

Number inventories are displayed and exported as compressed ranges; a wrong run boundary or tail misstates which numbers are owned.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
run and singleton	`["5550130-32", "5550180"]`	`["5550130-2", "5550180"]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.