Is Time Needed to Inform All Employees easy or hard?

The problem is rated Medium because it requires recognizing that the manager array forms a tree and then applying DFS or BFS traversal. The implementation itself is straightforward once the tree representation is built, but identifying the longest propagation path is the key step.

Time Needed to Inform All Employees Python/Java solution

Python and Java implementations usually build an adjacency list using a dictionary or ArrayList. A DFS function recursively visits each subordinate while accumulating the total time, updating a global or returned maximum. The algorithm processes each node once, producing an O(n) solution.

How to solve Time Needed to Inform All Employees in O(n)?

Build a graph where each manager stores a list of direct subordinates. Start traversal from the head employee and accumulate the time taken along the path. Track the maximum time encountered while visiting nodes using DFS or BFS. Since every employee is processed once, the overall complexity remains O(n).

What is the best approach for Time Needed to Inform All Employees?

Depth-First Search on the management tree is the most common approach. Convert the manager array into an adjacency list of manager to subordinates, then compute the longest time from the head to any employee. This runs in O(n) time because each employee is visited exactly once.

Is Time Needed to Inform All Employees asked at Google/Amazon/Meta?

This problem represents a common interview pattern involving tree traversal and propagation through hierarchies. Variations of this problem appear in interviews at companies like Amazon, Google, and Meta where candidates must model organizational structures as trees and compute longest propagation paths.

What data structure is used in Time Needed to Inform All Employees?

The main data structure is an adjacency list representing a tree or directed graph from manager to subordinates. Traversal is then performed using either a recursion stack for DFS or a queue for BFS to propagate the information through the hierarchy.

What is the time complexity of Time Needed to Inform All Employees?

Both DFS and BFS solutions run in O(n) time where n is the number of employees. Each node in the management tree is processed once while propagating the inform time. The space complexity is also O(n) due to the adjacency list and recursion stack or queue.

Description Hints 3 Solution Video 10:42

1376. Time Needed to Inform All Employees

Medium60.6% acceptance5 companies

A company has n employees with a unique ID for each employee from 0 to n - 1. The head of the company is the one with headID.

Each employee has one direct manager given in the manager array where manager[i] is the direct manager of the i-th employee, manager[headID] = -1. Also, it is guaranteed that the subordination relationships have a tree structure.

The head of the company wants to inform all the company employees of an urgent piece of news. He will inform his direct subordinates, and they will inform their subordinates, and so on until all employees know about the urgent news.

The i-th employee needs informTime[i] minutes to inform all of his direct subordinates (i.e., After informTime[i] minutes, all his direct subordinates can start spreading the news).

Return the number of minutes needed to inform all the employees about the urgent news.

Example 1:

Input: n = 1, headID = 0, manager = [-1], informTime = [0]
Output: 0
Explanation: The head of the company is the only employee in the company.

Example 2:

Input: n = 6, headID = 2, manager = [2,2,-1,2,2,2], informTime = [0,0,1,0,0,0]
Output: 1
Explanation: The head of the company with id = 2 is the direct manager of all the employees in the company and needs 1 minute to inform them all.
The tree structure of the employees in the company is shown.

Constraints: