Tiktok Viral Challenge

Problem Overview

• Count unique non-empty substrings of a video where non-viral letters (per engagementArray) do not exceed k.
• Inputs: string video (length n), integer k, engagementArray[26] with 0/1 for 'a'–'z'; Output: integer count of qualifying substrings.
• Constraints: 1≤n≤1500, 1≤k≤n, engagementArray[i]∈{0,1}.
• Real-world: model TikTok segment engagement to flag promising clip combinations.
• Asked in TikTok interviews; a coding interview problem and interview question.