690. Employee Importance

LeetCode 690. Employee Importance

Description

You are given a data structure of employee information, which includes the employee's unique id , their importance value and their direct subordinates' id.

For example, employee 1 is the leader of employee 2, and employee 2 is the leader of employee 3. They have importance value 15, 10 and 5, respectively. Then employee 1 has a data structure like [1, 15, [2]], and employee 2 has [2, 10, [3]], and employee 3 has [3, 5, []]. Note that although employee 3 is also a subordinate of employee 1, the relationship is not direct.

Now given the employee information of a company, and an employee id, you need to return the total importance value of this employee and all their subordinates.

Example 1:

Input: [[1, 5, [2, 3]], [2, 3, []], [3, 3, []]], 1
Output: 11
Explanation:
Employee 1 has importance value 5, and he has two direct subordinates: employee 2 and employee 3. They both have importance value 3. So the total importance value of employee 1 is 5 + 3 + 3 = 11.

Note:

1. One employee has at most one direct leader and may have several subordinates.

2. The maximum number of employees won't exceed 2000.

Tags

Hash Table, Depth-first Search, Breadth-first Search

Solution

We initialize a map from ID to corresponding employee for fast lookup. Then we push the given id into a queue, and do a while-loop until the queue is empty. In the loop, we pop an ID from the queue and get that employee struct, then increase the answer by this employee's Importance and push all Subordinates into the queue. At last, we return the accumulated answer.

Complexity

• Time complexity: $O(n)$

• Space complexity: $O(n)$

Code

func getImportance(employees []*Employee, id int) int {
	var ans int
	var q []int
	id2e := map[int]*Employee{}
	for _, e := range employees {
		id2e[e.Id] = e
	}
	if target, ok := id2e[id]; ok {
		ans += target.Importance
		q = append(q, target.Subordinates...)
	}
	for len(q) > 0 {
		sid := q[0]
		q = q[1:]
		if target, ok := id2e[sid]; ok {
			ans += target.Importance
			q = append(q, target.Subordinates...)
		}
	}
	return ans
}