Department Top Three Salaries solution and explanation

from collections import defaultdict

# Sample data
employees = [
    {'id': 1, 'name': 'Joe', 'salary': 85000, 'departmentId': 1},
    {'id': 2, 'name': 'Henry', 'salary': 80000, 'departmentId': 2},
    {'id': 3, 'name': 'Sam', 'salary': 60000, 'departmentId': 2},
    {'id': 4, 'name': 'Max', 'salary': 90000, 'departmentId': 1},
    {'id': 5, 'name': 'Janet', 'salary': 69000, 'departmentId': 1},
    {'id': 6, 'name': 'Randy', 'salary': 85000, 'departmentId': 1},
    {'id': 7, 'name': 'Will', 'salary': 70000, 'departmentId': 1}
]
departments = [
    {'id': 1, 'name': 'IT'},
    {'id': 2, 'name': 'Sales'}
]

# Group by department
dept_employees = defaultdict(list)
for emp in employees:
    dept_employees[emp['departmentId']].append(emp)

# Result
result = []

# Fetch top three salaries per department
for dept in departments:
    dept_id = dept['id']
    dept_name = dept['name']
    salaries = sorted(list(set(emp['salary'] for emp in dept_employees[dept_id])), reverse=True)[:3]
    
    # Add high earners
    for emp in dept_employees[dept_id]:
        if emp['salary'] in salaries:
            result.append({'Department': dept_name, 'Employee': emp['name'], 'Salary': emp['salary']})

# Print result
for r in result:
    print(r)

const employees = [
    {id: 1, name: 'Joe', salary: 85000, departmentId: 1},
    {id: 2, name: 'Henry', salary: 80000, departmentId: 2},
    {id: 3, name: 'Sam', salary: 60000, departmentId: 2},
    {id: 4, name: 'Max', salary: 90000, departmentId: 1},
    {id: 5, name: 'Janet', salary: 69000, departmentId: 1},
    {id: 6, name: 'Randy', salary: 85000, departmentId: 1},
    {id: 7, name: 'Will', salary: 70000, departmentId: 1}
];
const departments = [
    {id: 1, name: 'IT'},
    {id: 2, name: 'Sales'}
];

const groupByDepartment = (employees) => {
    const deptMap = new Map();
    employees.forEach(emp => {
        if (!deptMap.has(emp.departmentId)) {
            deptMap.set(emp.departmentId, []);
        }
        deptMap.get(emp.departmentId).push(emp);
    });
    return deptMap;
};

const deptEmployees = groupByDepartment(employees);

const result = [];

for (let {id, name} of departments) {
    const empList = deptEmployees.get(id);
    const uniqueSalaries = [...new Set(empList.map(emp => emp.salary))];
    uniqueSalaries.sort((a, b) => b - a);
    const topSalaries = uniqueSalaries.slice(0, 3);

    empList.forEach(emp => {
        if (topSalaries.includes(emp.salary)) {
            result.push({Department: name, Employee: emp.name, Salary: emp.salary});
        }
    });
}

console.log(result);

import java.util.*;

public class TopSalaries {
    static class Employee {
        int id;
        String name;
        int salary;
        int departmentId;

        Employee(int id, String name, int salary, int departmentId) {
            this.id = id;
            this.name = name;
            this.salary = salary;
            this.departmentId = departmentId;
        }
    }

    static class Department {
        int id;
        String name;

        Department(int id, String name) {
            this.id = id;
            this.name = name;
        }
    }

    public static void main(String[] args) {
        List<Employee> employees = Arrays.asList(
                new Employee(1, "Joe", 85000, 1),
                new Employee(2, "Henry", 80000, 2),
                new Employee(3, "Sam", 60000, 2),
                new Employee(4, "Max", 90000, 1),
                new Employee(5, "Janet", 69000, 1),
                new Employee(6, "Randy", 85000, 1),
                new Employee(7, "Will", 70000, 1)
        );

        List<Department> departments = Arrays.asList(
                new Department(1, "IT"),
                new Department(2, "Sales")
        );

        Map<Integer, List<Employee>> deptEmployees = new HashMap<>();
        for (Employee emp : employees) {
            deptEmployees.computeIfAbsent(emp.departmentId, k -> new ArrayList<>()).add(emp);
        }

        for (Department dept : departments) {
            int deptId = dept.id;
            String deptName = dept.name;

            List<Employee> empList = deptEmployees.get(deptId);
            if (empList == null) continue;

            empList.sort((a, b) -> Integer.compare(b.salary, a.salary));
            Set<Integer> topSalaries = new HashSet<>();
            List<Employee> result = new ArrayList<>();
            for (Employee emp : empList) {
                if (topSalaries.size() < 3 || topSalaries.contains(emp.salary)) {
                    topSalaries.add(emp.salary);
                    result.add(emp);
                }
                if (topSalaries.size() == 3 && !topSalaries.contains(emp.salary)) break;
            }

            for (Employee resEmp : result) {
                System.out.println("Department: " + deptName + ", Employee: " + resEmp.name + ", Salary: " + resEmp.salary);
            }
        }
    }
}

SELECT
    Department.NAME AS Department,
    Employee.NAME AS Employee,
    Salary
FROM
    Employee,
    Department
WHERE
    Employee.DepartmentId = Department.Id
    AND (
        SELECT
            COUNT(DISTINCT e2.Salary)
        FROM Employee AS e2
        WHERE e2.Salary > Employee.Salary AND Employee.DepartmentId = e2.DepartmentId
    ) < 3;