Leetcode 1412. Find the Quiet Students in All Exams

Given m exam rankings/scores for the same n students, identify all students who are "quiet" — i.e., for every other student j there exists at least one exam where the candidate scores lower than j (so they never strictly beat that student across all exams). The core challenge is aggregating pairwise dominance across exams and efficiently computing the intersection of these relations (via graph reachability, bitsets, or similar) to handle large n and m.