Leetcode 1376. Time Needed to Inform All Employees

Given a tree-structured company hierarchy rooted at headID where each employee i takes informTime[i] minutes to notify its direct subordinates, compute the minimum time to inform all employees — equivalently the maximum accumulated informTime along any root-to-leaf path. n can be up to 1e5, so solve with a linear-time tree traversal (DFS/BFS) to accumulate max times.