#440 · #1376 · Time Needed to Inform All Employees(通知所有员工所需的时间)

A company has n employees with a unique head, given by headID and the manager array. Each manager takes informTime[i] minutes to inform their direct reports, who then inform theirs in parallel. Return the total minutes needed to inform all employees. Constraints: 1 <= n <= 10^5, 0 <= headID < n; the manager relation forms a tree.