Add solution for Challenge 3 by clgp-aint-cool (#1560)

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PR: #1560
Author: @clgp-aint-cool

Author: clgp-aint-cool

challenge-3/submissions/clgp-aint-cool/solution-template.go

@@ -0,0 +1,66 @@
+package main
+
+import "fmt"
+
+type Employee struct {
+	ID     int
+	Name   string
+	Age    int
+	Salary float64
+}
+
+type Manager struct {
+	Employees []Employee
+}
+
+// AddEmployee adds a new employee to the manager's list.
+func (m *Manager) AddEmployee(e Employee) {
+    m.Employees = append(m.Employees,e)
+}
+
+// RemoveEmployee removes an employee by ID from the manager's list.
+func (m *Manager) RemoveEmployee(id int) {
+	for i, e := range m.Employees {
+		if e.ID == id {
+			m.Employees = append(m.Employees[:i], m.Employees[i+1:]...)
+		}
+	}
+}
+
+// GetAverageSalary calculates the average salary of all employees.
+func (m *Manager) GetAverageSalary() float64 {
+    if len(m.Employees) == 0 {
+		return 0
+	}
+	var totalSalary float64 = 0
+
+    for i:= range m.Employees{
+        totalSalary += m.Employees[i].Salary         
+    }
+    
+	return totalSalary / float64(len(m.Employees))
+}
+
+// FindEmployeeByID finds and returns an employee by their ID.
+func (m *Manager) FindEmployeeByID(id int) *Employee {
+    for i:=range m.Employees{
+        if m.Employees[i].ID == id {
+            return &m.Employees[i]
+        } 
+    }
+    return nil
+}
+
+func main() {
+	manager := Manager{}
+	manager.AddEmployee(Employee{ID: 1, Name: "Alice", Age: 30, Salary: 70000})
+	manager.AddEmployee(Employee{ID: 2, Name: "Bob", Age: 25, Salary: 65000})
+	manager.RemoveEmployee(1)
+	averageSalary := manager.GetAverageSalary()
+	employee := manager.FindEmployeeByID(2)
+
+	fmt.Printf("Average Salary: %f\n", averageSalary)
+	if employee != nil {
+		fmt.Printf("Employee found: %+v\n", *employee)
+	}
+}