690. Employee Importance

1. 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.

2. Example

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.

3. Note

• One employee has at most one direct leader and may have several subordinates.
• The maximum number of employees won’t exceed 2000.

4. Solutions

My Accepted Solution

n = i_employees.size()
Time complexity: O(n)
Space complexity: O(n)

// breadth-first search

class Solution 
{
private:
    unordered_map<int, Employee*> employeeOfId;
public:
    // int getImportance(vector<Employee*> employees, int id)
    int getImportance(vector<Employee*> &i_employees, int id) 
    {
        for(auto employee : i_employees)
            employeeOfId[employee->id] = employee;
        
        int result = 0;
        queue<Employee*> subordinates{{employeeOfId[id]}};
        for(Employee* employee; !subordinates.empty(); )
        {
            employee = subordinates.front();
            subordinates.pop();
            
            result += employee->importance;
            for(int i = 0; i < employee->subordinates.size(); i++)
                subordinates.push(employeeOfId[employee->subordinates[i]]);
        }
        
        return result;
    }
};