Count Ordered Pairs Whose Concatenation Equals a Target

Also reported as Access Code Fragments

OACapital OneLast reported January 2026Medium Frequency

Problem Overview

A oa question, reconstructed from 4 candidate reports. Sign in to read the write-up.

The problem statement — full requirements, constraints, and edge cases
Approach and trade-offs — what passing candidates did, and the mistakes that sink people

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Verified Source

Every question is reconstructed from multiple independent candidate reports. Follow-ups candidates reported, not invented ones.

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Interviewer Follow-ups

The follow-ups candidates reported, with the trigger that prompts each one — plus the mistakes that sink people.