Count Groups

Problem Overview

• Given an array of cable tags, for each query [l, r] count how many disjoint pairs of equal tags exist in the subarray.
• Input: tags and list of queries; Output: array of counts per query; each group is two cables; each cable used at most once; queries independent.
• Real-world context: Twilio IT distributing USB cables labeled by type tags.
• From Twilio interviews; a coding interview problem and interview question; constraints unspecified.