Technical Screen

Tracking the Earliest Unrepeated Visitor

UberSoftware Engineer · Technical Screen · Aug 2026

An Uber phone-screen report describes a data-structure exercise for recording ID visits and retrieving the earliest ID seen exactly once. The task includes a defined result when no eligible ID remains and permits keeping the data in memory, with IDs ranging to roughly one million. The follow-up asks how to make queries constant time. The reported hint involves removing repeated IDs from the front…

Shared by a candidate · reported Aug 2026. Interview formats change; use it as a guide, not a script.