Top K Frequent Security Events

Problem

Given a list of log lines logs, where each line is a string in the format "timestamp source severity event_id message", and an integer k, return the k most frequent event_id values among lines whose severity is at least min_severity. Severity order is DEBUG < INFO < WARN < ERROR < CRITICAL. If two event IDs have the same frequency, return the lexicographically smaller one first. Ignore malformed lines.

Constraints

• 1 <= len(logs) <= 10^5
• 1 <= k <= 10^4
• Each valid log line contains at least 5 space-separated fields
• min_severity is one of DEBUG, INFO, WARN, ERROR, CRITICAL