Process Logs

Problem Overview

• Identify user IDs involved in at least threshold transactions across logs as sender or recipient.
• Input: array of "sender recipient amount" strings (unordered) and an integer threshold; Output: user IDs as strings, sorted by numeric value.
• Constraints: up to 1e5 logs; IDs/amounts are digits, non-zero-starting, length 1–9; result has at least one ID.
• Real-world: detect suspicious activity in money transfer logs; asked in Ibm interviews; a coding interview interview question problem.