Leetcode 851. Loud and Rich

Given an acyclic directed graph of richer->poorer relations and a quietness score per person, compute for each person the quietest person among all people who are definitely at least as rich (i.e., all ancestors in the richer graph). This is a reachability/min-propagation problem on a DAG, typically solved by DFS with memoization or topological DP to propagate the minimum-quiet index.